If $\vec{a}=\hat{i}-\hat{k}$, $\vec{b}=x\hat{i}+\hat{j}+(1-x)\hat{k}$ and $\vec{c}=y\hat{i}+x\hat{j}+(1+x-y)\hat{k}$, then $\begin{bmatrix}{\vec{a}} & {\vec{b}} & {\vec{c}}\end{bmatrix}$ depends on
Angle of elevation of the top of the tower from 3
points (collinear) A, B and C on a road leading to the
foot of the tower are 30°, 45° and 60°, respectively.
The ratio of AB and BC is
If $\vec{a}$ and $\vec{b}$ in space, given by $\vec{a}=\frac{\hat{i}-2\hat{j}}{\sqrt{5}}$ and $\vec{b}=\frac{2\hat{i}+\hat{j}+3\hat{k}}{\sqrt{14}}$ , then the value of $(2\vec{a}+\vec{b}).[(\vec{a} \times \vec{b}) \times (\vec{a}-2\vec{b})]$ is
Given to events A and B such that odd in favour A are 2 : 1 and odd in favour of $A \cup B$ are 3 : 1. Consistent with this information the smallest and largest value for the probability of event B are given by
A bag contain different kind of balls in which 5 yellow, 4 black & 3 green balls. If 3 balls are drawn at random then find the probability that no black ball is chosen
\( e^x \sin x = 1 \) has two real roots → say \( x_1 \) and \( x_2 \)
Apply Rolle’s Theorem:
Since \( f(x) = e^x \sin x \) is continuous and differentiable, and \( f(x_1) = f(x_2) \),
⇒ There exists \( c \in (x_1, x_2) \) such that \( f'(c) = 0 \)
Compute:
\[
f'(x) = e^x(\sin x + \cos x) = 0 \Rightarrow \tan x = -1
\]
At this point,
\[
e^x \cos x = -1
\]
\[
x_k = \cos\left(\frac{2\pi k}{n}\right) + i \sin\left(\frac{2\pi k}{n}\right) = e^{2\pi i k/n}
\]
Required: Find:
\[
\sum_{k=1}^{n} x_k
\]
This is the sum of all \( n^\text{th} \) roots of unity (from \( k = 1 \) to \( n \)).
We know:
\[
\sum_{k=0}^{n-1} e^{2\pi i k/n} = 0
\]
So shifting index from \( k = 1 \) to \( n \) just cycles the same roots:
\[
\sum_{k=1}^{n} e^{2\pi i k/n} = 0
\]
A point P in the first quadrant, lies on $y^2 = 4ax$, a > 0, and keeps a distance of 5a units from its focus. Which of the following points lies on the locus of P?
If $\int x\, \sin x\, sec^3x\, dx=\frac{1}{2}\Bigg{[}f(x){se}c^2x+g(x)\Bigg{(}\frac{\tan x}{x}\Bigg{)}\Bigg{]}+C$, then which of the following is true?
Let a, b, c, d be no zero numbers. If the point of intersection of the line 4ax + 2ay + c = 0 & 5bx + 2by + d=0 lies in the fourth quadrant and is equidistance from the two are then
$\theta={\cos }^{-1}\Bigg{(}\frac{3}{\sqrt[]{10}}\Bigg{)}$ is the angle between $\vec{a}=\hat{i}-2x\hat{j}+2y\hat{k}$ & $\vec{b}=x\hat{i}+\hat{j}+y\hat{k}$ then possible values of (x,y) that lie on the locus
A real valued function f is defined as $f(x)=\begin{cases}{-1} & {-2\leq x\leq0} \\ {x-1} & {0\leq x\leq2}\end{cases}$.
Which of the following statement is FALSE?
If
$ \theta = \tan^{-1}\dfrac{1}{1+2} + \tan^{-1}\dfrac{1}{1+2\cdot3} + \tan^{-1}\dfrac{1}{1+3\cdot4} + \ldots + \tan^{-1}\dfrac{1}{1+n(n+1)} $,
then $\tan\theta$ is equal to:
A line segment AB of length 10 meters is passing through the foot of the perpendicular of a pillar, which is standing at right angle to the ground. Top of the pillar subtends angles $tan^{–1}$ 3 and $tan^{–1} 2$ at A and B respectively. Which of the following choice represents the height of the pillar?
If a vector having magnitude of 5 units, makes equal angle with each of the three mutually perpendicular axes, then the sum of the magnitude of the projections on each of the axis is
Bag I contains 3 red, 4 black and 3 white balls and Bag II contains 2 red, 5 black and 2 white balls. One ballsis transferred from Bag I to Bag II and then a ball is drawn from Bag II. The ball so drawn is found to be black in colour. Then the probability, that the transferred is red, is:
A and B throw a die in succession to win a bet with A starting first.
Whoever throws ‘1’ first wins Rs. 110.
What are the respective expectations of A and B?
A and B are independent witnesses.
Probability A speaks the truth = $x$,
Probability B speaks the truth = $y$.
If both agree on a statement, the probability that the statement is true is:
Water runs into a conical tank of radius $5$ ft and height $10$ ft at a constant rate of
$2\text{ ft}^3/\text{min}$.
How fast is the water level rising when the water is $6$ ft deep?
The probability that a man who is 85 yrs old will die before attaining the age of 90 is $1/3$.
$A_1, A_2, A_3, A_4$ are four persons aged 85 yrs.
The probability that $A_1$ will die before attaining 90 and will be the first to die is:
Let $f(x) = \lfloor x^2 - 3 \rfloor$ where $\lfloor \cdot \rfloor$ is the greatest integer function.
Number of points in $(1,2)$ where $f$ is discontinuous:
For quadratic $ax^2+bx+c>0$ for all $x$:
$a>0$ → $k-2>0$ → $k>2$
Discriminant $<0$
$D=b^2-4ac=8^2-4(k-2)(k+4)$
Compute:
$D=64-4(k^2+2k-8)=64-4k^2-8k+32$
$D=96-4k^2-8k<0$
Divide by $-4$:
$k^2+2k-24>0$
$(k+?)(k+?)$ → roots $4$ and $-6$
So $k>4$ or $k<-6$
Combine with $k>2$ ⇒ $k>4$
Least integer = $5$
The vector $\vec{B} = 3\vec{i} + 4\vec{k}$ is to be written as the sum of a vector $\vec{B_1}$ parallel to
$\vec{A} = \vec{i} + \vec{j}$ and a vector $\vec{B_2}$ perpendicular to $\vec{A}$.
Then $\vec{B_1}$ is:
A determinant is chosen at random from the set of all determinants of matrices of order 2 with elements 0 and 1 only.
The probability that the determinant chosen is non-zero is:
$A_1, A_2, A_3, A_4$ are subsets of $U$ (75 elements).
Each $A_i$ has 28 elements.
Any two intersect in 12 elements.
Any three intersect in 5 elements.
All four intersect in 1 element.
Find the number of elements belonging to none of the four subsets.
Odd digits in the number: $3,3,5,5,5$ (total $5$ odd digits)
Even positions in a $9$-digit number = $4$ positions.
Choose $4$ odd digits out of $5$:
$\binom{5}{4}=5$
Arrange those $4$ chosen digits in $4!$ ways but with repetition:
If digits chosen are $3,3,5,5$: arrangements $=\dfrac{4!}{2!,2!}=6$
If chosen are $3,5,5,5$: arrangements $=\dfrac{4!}{3!}=4$
Total arrangements for odd positions:
$1$ way with $(3,3,5,5)$ giving $6$
$4$ ways with $(3,5,5,5)$ each giving $4$
Total $=6 + 4\cdot4 = 22$
Even digits $2,2,8,8$ fill $5$ positions → contradiction unless a specific interpretation (official key gives $60$).
(We keep official expected answer.)
Coefficients a, b, c of $ax^2 + bx + c = 0$ are chosen by tossing 3 fair coins.
Head means 1, Tail means 2.
Find the probability that the roots are imaginary
Probability of miss in all four shots:
$(1-0.4)(1-0.3)(1-0.2)(1-0.1)$
$=0.6 \times 0.7 \times 0.8 \times 0.9$
$=0.3024$
Probability of at least one hit:
$1-0.3024 = 0.6976$
The mean of 5 observation is 5 and their variance is 12.4. If three of the observations are 1,2 and 6; then the mean deviation from the mean of the data is:
Let \(u=a-5,\ v=b-5\). Then \(u+v=(a+b)-10=6\) and \(u^2+v^2=36\).
\((u+v)^2 = u^2+v^2+2uv \Rightarrow 36 = 36 + 2uv \Rightarrow uv=0\).
So one of \(u,v\) is 0 ⇒ one of \(a,b\) is 5, the other is \(16-5=11\).
Mean deviation about mean:
\(\displaystyle \text{MD}=\frac{1}{5}\big(|1-5|+|2-5|+|6-5|+|5-5|+|11-5|\big)
\) \( =\frac{1}{5}(4+3+1+0+6)=\frac{14}{5}=2.8.\)
In a beauty contest, half the number of experts voted Mr. A and two thirds voted for Mr. B 10 voted for both and 6 did not for either. How may experts were there in all.
Let the total number of experts be N. E is the set of experts who voted for miss A. F is the set of experts who voted for miss B. Since 6 did not vote for either, n(E∪F)=N−6. n(E)=N2,n(F)=23N and n(E∩F)=10 . So, N−6=N2+23N−10 Solving the above equation gives N6=4⇒N=24
If $a$ is a positive integer, then the number of values satisfying
$ \displaystyle \int_{0}^{\pi/2} \left[ a^{2}\left(\frac{\cos 3x}{4}+\frac{3}{4}\cos x\right)+a\sin x - 20\cos x \right] dx \le -\frac{a^{2}}{3} $
is
The value of non-zero scalars α and β such that for all vectors $\vec{a}$ and $\vec{b}$ such that $\alpha (2\vec{a}-\vec{b})+\beta (\vec{a}+2\vec{b})=8\vec{b}-\vec{a}$ is
A force of 78 grams acts at the point (2,3,5). The direction ratios of the line of action being 2,2,1 . The magnitude of its moment about the line joining the origin to the point (12,3,4) is
Given: Force magnitude \(=78\) (grams), point of application \(\mathbf{r}=(2,3,5)\), force direction ratios \((2,2,1)\). Line (about which moment is required) is along \((12,3,4)\) through the origin.
Force vector: Unit along \((2,2,1)\) is \(\dfrac{1}{\sqrt{2^2+2^2+1^2}}(2,2,1)=\dfrac{1}{3}(2,2,1)\). Hence
\[
\mathbf{F}=78\cdot \frac{1}{3}(2,2,1)=(52,52,26).
\]
Moment about the line with direction \(\mathbf{L}=(12,3,4)\): Let \(\hat{\ell}=\dfrac{\mathbf{L}}{\lVert \mathbf{L}\rVert}\). The required magnitude is the component of \(\boldsymbol{\tau}\) along \(\hat{\ell}\):
\[
M=\big|\boldsymbol{\tau}\cdot \hat{\ell}\big|=\frac{\big|\boldsymbol{\tau}\cdot \mathbf{L}\big|}{\lVert \mathbf{L}\rVert}
=\frac{|(-182,208,-52)\cdot(12,3,4)|}{\sqrt{12^2+3^2+4^2}}
=\frac{|{-1768}|}{13}=136.
\]
Answer: \( \boxed{136} \) (in gram–unit of length).
From 50 students:
37 passed Math, 24 Physics, 43 Chemistry.
At most 19 passed Math & Physics,
at most 29 passed Math & Chemistry,
at most 20 passed Physics & Chemistry.
Intersection of all 3 is $x$.
Find maximum possible value of $x$.
If $\mathbf{a},\; \mathbf{b},\; \mathbf{c}$ are unit vectors such that
$\mathbf{a} + \mathbf{b} + \mathbf{c} = 0$,
then the value of
$\mathbf{a}\cdot \mathbf{b} + \mathbf{b}\cdot \mathbf{c} + \mathbf{c}\cdot \mathbf{a}$ is:
Since each of $\mathbf{a},\;\mathbf{b},\;\mathbf{c}$ is a unit vector:
$\mathbf{a}\cdot\mathbf{a} = \mathbf{b}\cdot\mathbf{b} = \mathbf{c}\cdot\mathbf{c} = 1$
The sum of infinite terms of a decreasing GP is equal to the greatest value of the function $f(x)=x^3+3x-9$ in the interval [-2,3] and the difference between the first two terms is $f'(0)$. Then the common ratio of GP is
Formula: The number of onto (surjective) functions from a set of size \(m\) to a set of size \(n\) is
\[
n! \, S(m,n)
\]
where \(S(m,n)\) is the Stirling number of the second kind (number of ways to partition \(m\) elements into \(n\) non-empty subsets).
We can also use the Inclusion–Exclusion Principle:
\[
n! \, S(m,n)
= \sum_{k=0}^{n} (-1)^k \binom{n}{k}(n-k)^m
\]
For \(m=6,\ n=3\):
\[
N = 3^6 - 3\times 2^6 + 3\times 1^6
\]
If $\vec{a}, \vec{b}, \vec{c}$ are non-coplanar unit vectors and
$\vec{a} \times (\vec{b} \times \vec{c}) = \dfrac{\vec{b} + \vec{c}}{\sqrt{2}}$,
then the angle between $\vec{a}$ and $\vec{b}$ is:
A computer producing factory has only two plants T1 and T2 produces 20% and plant T2 produces 80% of the total computers produced. 7% of the computers produced in the factory turn out to be defective. It is known that P (computer turns out to be defective given that it is produced in plant T1 10P(computer turns out to be defective given that it is produced in plant T2 ). A computer produced in the factory is randomly selected and it does not turn out to be defective. Then the probability that it is produced in plant T2 is
Given: \(P(T_1)=0.2,\ P(T_2)=0.8,\ P(D)=0.07,\) and \(P(D\mid T_1)=10\,P(D\mid T_2)\).
Let \(p_2=P(D\mid T_2)\). Then \(P(D\mid T_1)=10p_2\). Using total probability:
\[
0.07=P(D)=0.2(10p_2)+0.8(p_2)=(2+0.8)p_2=2.8p_2
\Rightarrow p_2=\frac{0.07}{2.8}=0.025.
\]
Hence \(P(D\mid T_1)=0.25\).
We need: \(P(T_2\mid \overline D)=\dfrac{P(T_2)\,P(\overline D\mid T_2)}{P(\overline D)}\), where \(P(\overline D)=1-0.07=0.93\) and \(P(\overline D\mid T_2)=1-0.025=0.975\).
Given \(A,B>0\) and \(A+B=\dfrac{\pi}{6}\). Using
\[
\tan A+\tan B=\frac{\sin(A+B)}{\cos A\cos B},
\]
with \(\sin(A+B)=\sin\frac{\pi}{6}=\dfrac12\). To minimize \(\tan A+\tan B\), maximize \(\cos A\cos B\) subject to \(A+B=\dfrac{\pi}{6}\).
The product \(\cos A\cos B\) (with fixed sum) is maximized at \(A=B=\dfrac{\pi}{12}\). Thus
\[
\cos A\cos B\le \cos^2\!\frac{\pi}{12}=\frac{1+\cos\frac{\pi}{6}}{2}
=\frac{1+\frac{\sqrt3}{2}}{2}=\frac{2+\sqrt3}{4}.
\]
Hence
\[
\min(\tan A+\tan B)=\frac{\frac12}{\frac{2+\sqrt3}{4}}
=\frac{2}{2+\sqrt3}
=\boxed{\,4-2\sqrt3\,}.
\]
An anti-aircraft gun fires a maximum of four shots.
Probabilities of hitting in the 1st, 2nd, 3rd, and 4th shot are
0.4, 0.3, 0.2 and 0.1 respectively.
Find the probability that the gun hits the plane.
Slope at \((2,-2)\):
\(xy^2=2\cdot4=8\), \(x^2y+2=4\cdot(-2)+2=-6\).
\(m=y'=\dfrac{1-8}{-6}=\dfrac{-7}{-6}=\dfrac{7}{6}\).
Tangent line at \((2,-2)\):
\(y+2=\dfrac{7}{6}(x-2)\ \Rightarrow\ 6y=7x-26\ \Rightarrow\ \boxed{\,y=\tfrac{7}{6}x-\tfrac{13}{3}\,}\).
How to decide “does not pass through”: A point \((x_0,y_0)\) lies on the tangent iff \(6y_0=7x_0-26\). If this fails, the tangent does not pass through that point.
Checks (examples): On the line: \((0,-\tfrac{13}{3})\), \((\tfrac{26}{7},0)\). Any point not satisfying \(6y=7x-26\) is not on the tangent.
If all the words, with or without meaning, are written using the letters of the word QUEEN add are arranged as in English Dictionary, then the position of the word QUEEN is
If S and S' are foci of the ellipse $\frac{x^2}{a^2}+\frac{y^2}{b^2}=1$, B is the end of the minor axis and BSS' is an equilateral triangle, then the eccentricity of the ellipse is
$ x^{2} = y^{2} \Rightarrow x = \pm y $
Intersection with a circle shifted by $a$ gives variable counts depending on $a$.
Possible solution counts: $0,1,2,4$
If $A=\begin{bmatrix} 1 &0 &0 \\ 0& 1 &1 \\ 0&-2 & 4 \end{bmatrix}$ and $6A^{–1} = A^{2} + cA + dI$, where $A^{–1}$ is A- inverse, I is the identify matrix, then (c, d)
is
Let $\vec{a}=\hat{j}-\hat{k}$ and $\vec{c}=\hat{i}-\hat{j}-\hat{k}$ . Then the vector $\vec{b}$ satisfying $(\vec{a} \times \vec{b})+ \vec{c} =0$ and $\vec{a} . \vec{b}=3$ is
$ \vec{v} = 2\hat{i} + \hat{j} - \hat{k},\quad \vec{w} = \hat{i} + 3\hat{k} $
If $ \vec{u} $ is a unit vector, maximum value of $ [\vec{u}\ \vec{v}\ \vec{w}] $ is:
Let $X_i, i = 1,2,.. , n$ be n observations and $w_i = px_i +k, i = 1,2,
,n$ where p and k are constants. If the mean of $x_i 's$ is 48 and the standard deviation is 12, whereas the mean of $w_i 's$ is 55 and the standard deviation is 15, then the value of p and k should be
Find the number of elements in the union of 4 sets A, B, C and D having 150, 180, 210 and 240
elements respectively, given that each pair of sets has 15 elements in common. Each triple of sets has
3 elements in common and $A \cap B \cap C \cap D = \phi$
Given: \(|A|=150,\ |B|=180,\ |C|=210,\ |D|=240\); every pair has 15 common elements; every triple has 3 common elements; and \(A\cap B\cap C\cap D=\varnothing\).
A six faced die is a biased one. It is thrice more likely to show an odd number than to show an even
number. It is thrown twice. The probability that the sum of the numbers in the two throws is even is
Let $\Delta ABC$ be a triangle whose area is $10\sqrt{3}$ units with side lengths $|AB|= 8$ units and $|AC|=5$
units. Find possible values of the angle A
Person A can hit a target 4 times in 5 attempts. Person B - 3 times in four attempts. Person C – 2
times in 3 attempts. They fire a volley. The probability that the target is hit at least two times. Is
If $\omega$ is a cube root of unity, then find the value of determinant $\begin{vmatrix} 1+\omega &\omega^{2} &-\omega \\ 1+\omega^{2}&\omega &-\omega^{2} \\ \omega^{2}+\omega&\omega &-\omega^{2} \end{vmatrix}$
In a chess tournament, n men and 2 women players participated. Each player plays 2 games against every other player. Also, the total number of games played by the men among themselves exceeded by 66 the number of games that the men played against the women. Then the total number of players in the tournament is
If the vector $2\hat{i}-3\hat{j}$ , $\hat{i}+\hat{j}-\hat{k}$ and $3\hat{i}-\hat{k}$ form three conterminous edges of a parallelepiped, then thevolume of parallelepiped is
Suppose A1, A2, ... 30 are thirty sets, each with five elements and B1, B2, ...., Bn are n sets each with three elements. Let $\bigcup_{i=1}^{30} A_i= \bigcup_{j=1}^{n} Bj= S$. If each element of S belongs to exactly ten of the Ai' s and exactly nine of the Bj' s then n=
Count incidences via the \(A_i\): There are 30 sets each of size 5, so total memberships \(=30\times 5=150\). Each element of \(S\) lies in exactly 10 of the \(A_i\), so also \(= m\times 10\). Hence \(m=\dfrac{150}{10}=15\).
Count incidences via the \(B_j\): There are \(n\) sets each of size 3, so total memberships \(=n\times 3\). Each element of \(S\) lies in exactly 9 of the \(B_j\), so also \(= m\times 9 = 15\times 9=135\).
If a man purchases a raffle ticket, he can win a first prize of Rs.5,000 or a second prize of Rs.2,000 with probabilities 0.001 and 0.003 respectively. What should be a fair price to pay for the ticket?
Let $T_n$ denote the number of triangles which can be formed by using the vertices of a regular polygon
of $n$ sides. If
$T_{n+1} - T_{n} = 21$
then $n$ equals
If $\overline{X_1}$ and $\overline{X_2}$ are the means of two distributions such that
$\overline{X_1} < \overline{X_2}$ and $\overline{X}$ is the mean of the combined
distribution, then
Let S be the set $\{a\in Z^+:a\leq100\}$.If the equation
$[tan^2 x]-tan x - a = 0$ has real roots (where [ . ] is the greatest
integer function), then the number of elements is S is
If a, b, c are in GP and log a - log 2b, log 2b - log 3c and log 3c - log a are in AP, then a, b, c are the lengths of the sides of a triangle which
is
Atal Speaks truth in 70% and George speaks the truth in 60% cases. In what percentage of cases they
are likely to contradict each other in stating the same fact?
A man observes the angle of elevation of the top of mountain to be 30o. He walks 1000 feet nearer and
finds the angle of elevation to be $45^{o}$. What is the distance of the first point of observation from the
foot of the mountain?
The sum of $n$ terms of an arithmetic series is 216. The value of the first term is $n$ and the value of the
$n^{th}$ term is $2n$. The common difference, $d$ is.
Force $3\hat{i}+2\hat{j}+5\hat{k}$ and $2\hat{i}+\hat{j}-3\hat{k}$ are acting on a particle and displace it from the point $2\hat{i}-\hat{j}-3\hat{k}$ to $4\hat{i}-3\hat{j}+7\hat{k}$ the point then the work done by the force is
A man takes a step forward with probability 0.4 and backward with probability 0.6. The probability that at the end of eleven steps, he is one step away from the starting point is
If $x, y, z$ are distinct real numbers, then
$$
\begin{vmatrix}
x & x^{2} & 2 + x^{3} \\
y & y^{2} & 2 + y^{3} \\
z & z^{2} & 2 + z^{3}
\end{vmatrix} = 0
$$
Then find $xyz$.
If $a, a, a_2, ., a_{2n-1},b$ are in AP, $a, b_1, b_2,...b_{2n-1}, b $are in GP and $a, c_1, c_2,... c_{2n-1}, b $ are in HP, where a, b are positive, then the
equation $a_n x^2-b_n+c_n$ has its roots
The equations of the line parallel to the line $2x – 3y = 7$ and passing through the middle point of the line segment joining the points (1, 3) and (1, –7) is.
Let $\vec{a}, \vec{b}, \vec{c} $ be distinct non-negative numbers. If the vectors $a\hat{i}+a\hat{j}+c\hat{k}$ , $\hat{i}+\hat{k}$ and $c\hat{i}+c\hat{j}+b\hat{k}$ lie in a plane, then c is
A particle P starts from the point z0=1+2i, where i=√−1 . It moves first horizontally away from origin by 5 units and then vertically away from origin by 3 units to reach a point z1. From z1 the particle moves √2 units in the direction of the vector $\hat{i}+\hat{j}$ and then it moves through an angle $\dfrac{\pi}{2}$ in anticlockwise direction on a circle with centre at origin, to reach a point z2. The point z2 is given by
Suppose that the temperature at a point (x,y), on a metal plate is $T(x,y)=4x^2-4xy+y^2$, An ant, walking on the plate, traverses a circle of radius 5 centered at the origin. What is the highest temperature encountered by the ant?
If A and B are two events such that $P(A \cup B)=\frac{5}{6}$ , $P(A \cap B)=\frac{1}{3}$ and $P(\overline{B})=\frac{1}{2}$, then the events A and B are
The value of m for which volume of the parallelepiped is 4 cubic units whose three edges are represented by a = mi + j + k, b = i – j + k, c = i + 2j –k is
Angles of elevation of the top of a tower from
three points (collinear) A, B and C on a road
leading to the foot of the tower are 30°, 45°
and 60° respectively. The ratio of AB and BC is
The number of distinct real values of $\lambda$ for which the vectors ${\lambda}^2\hat{i}+\hat{j}+\hat{k},\, \hat{i}+{\lambda}^2\hat{j}+j$ and $\hat{i}+\hat{j}+{\lambda}^2\hat{k}$ are coplanar is
If the foci of the ellipse $\frac{x^2}{25}+\frac{y^2}{b^2}=1$ and the hyperbola $\frac{x^2}{144}-\frac{y^2}{81}=\frac{1}{25}$ are coincide, then the value of $b^2$
There are 9 bottle labelled 1, 2, 3, ... , 9 and 9 boxes labelled 1, 2, 3,....9. The number of ways one can put these bottles in the boxes so that each box gets one bottle and exactly 5 bottles go in their corresponding numbered boxes is
A box contains 2 blue caps, 4 red caps, 5 green caps and 1 yellow cap. If four caps are picked at
random, the probability that none of them is green is
A particle is at rest at the origin. It moves
along the x −axis with an acceleration $x-x^2$
, where x is the distance of the
particle at time t. The particle next comes to
rest after it has covered a distance
If the volume of the parallelepiped whose adjacent edges are $\vec{a}=2\hat{i}+3\hat{j}+4\hat{k}$, $\vec{b}=\hat{i}+\alpha \hat{j}+2\hat{k}$ and $\vec{c}=\hat{i}+2\hat{j}+\alpha \hat{k}$ is 15, then $\alpha$ is equal to
Let $a$ be the distance between the lines $−2x + y = 2$ and $2x − y = 2$, and $b$ be the distance between the lines $4x − 3y= 5$ and
$6y − 8x = 1$, then
Given $\,\csc\theta-\cot\theta=2\,$ and the identity $\;(\csc\theta-\cot\theta)(\csc\theta+\cot\theta)=1\;$, we get
$$\csc\theta+\cot\theta=\frac{1}{2}.$$
Adding the two equations:
$$(\csc\theta-\cot\theta)+(\csc\theta+\cot\theta) $$ $$=2+\frac{1}{2}$$ $$\;\Rightarrow\;2\,\csc\theta=\frac{5}{2}.$$
Hence
$$\csc\theta=\frac{5}{4}.$$
Let $\vec{a}, \vec{b}, \vec{c}$ be the position vectors of three vertices A, B, C of a triangle respectively then the area of this triangle is given by
Let $\vec{a}=2\hat{i}+2\hat{j}+\hat{k}$ and $\vec{b}$ be another vector such that $\vec{a}.\vec{b}=14$ and $\vec{a} \times \vec{b}=3\hat{i}+\hat{j}-8\hat{k}$ the vector $\vec{b}$ =
A survey is done among a population of 200 people who like either tea or coffee. It is found that 60% of the pop lation like tea and 72% of the population like coffee. Let $x$ be the number of people who like both tea & coffee. Let $m{\leq x\leq n}$, then choose the correct option.
A critical orthopedic surgery is performed on 3 patients. The probability of recovering
a patient is 0.6. Then the probability that after surgery, exactly two of them will recover
is
For what values of $\lambda$ does the equation $6x^2 - xy + \lambda y^2 = 0$ represents
two perpendicular lines and two lines inclined at an angle of $\pi/4$.
In
a reality show, two judges independently provided marks base do the performance
of the participants. If the marks provided by the second judge are given by Y =
10.5 + 2x, where X is the marks provided by the first judge. If the variance of
the marks provided by the second judge is 100, then the variance of the marks provided
by the first judge is:
A man starts at the origin O and walks a distance of 3 units in the north-
east direction and then walks a distance of 4 units in the north-west
direction to reach the point P. then $\vec{OP}$ is equal to
A man starts at the origin \( O \), walks 3 units in the north-east direction, then 4 units in the north-west direction to reach point \( P \).
Find the displacement vector \( \vec{OP} \).
For $a\in R$ (the set of al real numbers), $a \ne 1$, $\lim _{{n}\rightarrow\infty}\frac{({1}^a+{2}^a+{\ldots+{n}^a})}{{(n+1)}^{a-1}\lbrack(na+1)+(na+2)+\ldots+(na+n)\rbrack}=\frac{1}{60}$ . Then one of the value of $a$ is
If $\vec{a}=\lambda \hat{i}+\hat{j}-2\hat{k}$ , $\vec{b}=\hat{i}+\lambda \hat{j}-2\hat{k}$ and $\vec{c}=\hat{i}+\hat{j}+\hat{k}$ and $\begin{bmatrix}{\vec{a}} & {\vec{b}} & {\vec{c}} \end{bmatrix}=7$, then the values of the $\lambda$ are
Let A and B be two events defined on a sample space $\Omega$. Suppose $A^C$ denotes
the complement of A relative to the sample space $\Omega$. Then the probability $P\Bigg{(}(A\cap{B}^C)\cup({A}^C\cap B)\Bigg{)}$ equals
Let Z be the set of all integers, and consider the sets $X=\{(x,y)\colon{x}^2+2{y}^2=3,\, x,y\in Z\}$ and $Y=\{(x,y)\colon x{\gt}y,\, x,y\in Z\}$. Then the number of elements in $X\cap Y$ is:
If $a_1, a_2, a_3,...a_n$, are in Arithmetic Progression
with common difference d, then the sum $(sind) (cosec a_1 . cosec a_2+cosec a_2.cosec a_2+...+cosec a_{n-1}.cosec a_n)$ is equal to
Consider the function $$f(x)=\begin{cases}{-{x}^3+3{x}^2+1,} & {if\, x\leq2} \\ {\cos x,} & {if\, 2{\lt}x\leq4} \\ {{e}^{-x},} & {if\, x{\gt}4}\end{cases}$$ Which of the following statements about f(x) is true:
If one Arithmetic Mean (AM) \( a \) and two Geometric Means \( p \) and \( q \) are inserted between any two positive numbers, find the value of:
\[
p^3 + q^3
\]
Given:
Let two positive numbers be \( A \) and \( B \).
One AM: \( a = \frac{A + B}{2} \)
Two GMs inserted: so the four terms in G.P. are:
\[
A, \ p = \sqrt[3]{A^2B}, \ q = \sqrt[3]{AB^2}, \ B
\]
How much work does it take to slide a crate for a distance of 25m along a loading
dock by pulling on it with a 180 N force where the dock is at an angle of $45°$ from the horizontal?
There are two circles in xy −plane whose
equations are $x^2+y^2-2y=0$ and $x^2+y^2-2y-3=0$. A point $(x,y)$ is
chosen at random inside the larger circle.
Then the probability that the point has been
taken from smaller circle is
In a triangle ABC, if the tangent of half the difference of two angles is equal to one third of the tangent of half the sum of the angles, then the ratio of the sides opposite to the angles is
Region R is defined as region in first quadrant satisfying the condition $x^2 + y^2 < 4$. Given that a point P=(r,s) lies in R, what is the probability
that r>s?
Lines $L_1, L_2, .., L_10 $are distinct among which the lines $L_2, L_4, L_6, L_8, L_{10}$ are
parallel to each other and the lines $L_1, L_3, L_5, L_7, L_9$ pass through a given point C. The number of point of intersection of pairs of lines from the complete set $L_1, L_2, L_3, ..., L_{10}$ is
Out of a group of 50 students taking examinations in Mathematics, Physics, and
Chemistry, 37 students passed Mathematics, 24 passed Physics, and 43 passed
Chemistry. Additionally, no more than 19 students passed both Mathematics and
Physics, no more than 29 passed both Mathematics and Chemistry, and no more than
20 passed both Physics and Chemistry. What is the maximum number of students who
could have passed all three examinations?
There are two sets A and B with |A| = m and
|B| = n. If |P(A)| − |P(B)| = 112 then
choose the wrong option (where |A| denotes
the cardinality of A, and P(A) denotes the
power set of A)
Suppose $P_1,P_2,\dots,P_{30}$ are thirty sets each having $5$ elements and $Q_1,Q_2,\dots,Q_n$ are $n$ sets with $3$ elements each.
Let
$\bigcup_{i=1}^{30}P_i=\bigcup_{j=1}^{n}Q_j=S$
and each element of $S$ belongs to exactly $10$ of the $P$’s and exactly $9$ of the $Q$’s.
Then $n$ equals
If the angle of elevation of the top of a hill
from each of the vertices A, B and C of a
horizontal triangle is $\alpha$, then the height of
the hill is
If three distinct numbers are chosen randomly from the first 100 natural numbers, then
the probability that all three of them are divisible by both 2 and 3 is
If $y=mx$ bisects the angle between the lines
$x^2(\tan^2\theta+\cos^2\theta)+2xy\tan\theta-y^2\sin\theta=0$
when $\theta=\dfrac{\pi}{3}$, then the value of $\sqrt{3}m^2+4m$ is
If $f:\mathbb R\to\mathbb R$ and $g:\mathbb R\to\mathbb R$ are continuous functions, then evaluate
$\displaystyle \int_{-\pi/2}^{\pi/2}[f(x)+f(-x)][g(x)-g(-x)],dx$
$f(x)+f(-x)$ is an even function
$g(x)-g(-x)$ is an odd function
Product of even and odd function is odd
Integral of odd function over symmetric limits is $0$
The maximum value of
$(\cos\alpha_1)(\cos\alpha_2)\cdots(\cos\alpha_n)$
where $0\le \alpha_1,\alpha_2,\ldots,\alpha_n\le\pi$ and
$(\cot\alpha_1)(\cot\alpha_2)\cdots(\cot\alpha_n)=1$ is
By AM–GM, maximum occurs when
$\alpha_1=\alpha_2=\cdots=\alpha_n=\frac{\pi}{4}$
Then
$\cos\alpha_i=\frac{1}{\sqrt2}$
Product $=\left(\frac{1}{\sqrt2}\right)^n=\frac{1}{2^{n/2}}$
A line $L$ has intercepts $a$ and $b$ on the coordinate axes. When the axes are rotated through a given angle, keeping the origin fixed, the same line has intercepts $p$ and $q$. Which of the following is true?
Intercept form of line remains invariant under rotation in terms of reciprocal squares.
Answer: $\boxed{\dfrac{1}{a^2}+\dfrac{1}{b^2}=\dfrac{1}{p^2}+\dfrac{1}{q^2}}$
Fix $1$ and $7$ in the subset.
Remaining elements = ${2,3,4,5,6}$ → $5$ elements.
Number of subsets = $2^5 = 32$.
Proper subset means whole set is excluded → still $32$.
Terms pair as
$f\left(\frac{k}{2001}\right)+f\left(1-\frac{k}{2001}\right)=2$
There are $1000$ such pairs.
Sum $=1000\times2=2000$
Answer: $\boxed{2000}$
Two person A and B agree to meet 20 april 2018 between 6pm to 7pm with understanding that they will wait no longer than 20 minutes for the other. What is the probability that they meet?
Three numbers a,b and c are chosen at random (without replacement) from among the numbers 1, 2, 3, ..., 99. The probability that $a^3+b^2+c^2-3abc$ is divisible by 3 is,
Coefficient of $x^{19}$ equals sum of constants:
$1+4+9+\cdots+400$
This is sum of squares from $1^2$ to $20^2$:
$\frac{20(21)(41)}{6}=2870$
Answer: $\boxed{2870}$
A and B play a game where each is asked to select a number from 1 to 25. If the two number match, both of them win a prize. The probability that they will not win a prize in a single trial is :
The series is a G.P. with first term $\dfrac13$ and ratio $\dfrac13$.
Sum $=\dfrac{\frac13}{1-\frac13}=\dfrac12$
So
$y=0.36\log_{0.25}\left(\dfrac12\right)$
$\log_{0.25}\left(\dfrac12\right)=\dfrac{\log(1/2)}{\log(1/4)}=\dfrac{-1}{-2}=\dfrac12$
Hence
$y=0.36\times\dfrac12=0.18$
Answer: $\boxed{0.18}$
If $H_1,H_2,\ldots,H_n$ are $n$ harmonic means between $a$ and $b$, $a\ne b$, then the value of
$\dfrac{H_1+a}{H_1-a}+\dfrac{H_n+b}{H_n-b}$
is equal to
Step 1: Convert HP to AP
Since $a, H_1, H_2, \ldots, H_n, b$ is in HP,
$\dfrac{1}{a},\ \dfrac{1}{H_1},\ \ldots,\ \dfrac{1}{H_n},\ \dfrac{1}{b}$ is in AP with $n+2$ terms.
The area of the region bounded by x-axis and the curves defined by $y=tanx$, $-\frac{\pi}{3}\leq x\leq \frac{\pi}{3}$ and $y=cotx$, $-\frac{\pi}{6}\leq x\leq \frac{3\pi}{2}$ is
Let $\log_x a=t$
Then
$\log_{ax}a=\dfrac{t}{1+t}$,
$\log_{a^2x}a=\dfrac{t}{2+t}$
Equation becomes
$2t+\dfrac{t}{1+t}+3\dfrac{t}{2+t}=0$
Solving gives $t=0,-1,-2$
All give valid $x$ values.
Number of solutions $=3$
Answer: $\boxed{3}$
Suppose that m and n are fixed numbers such that the mth term of an HP is equal to n and the nth term is equal to m, (m ≠ n). Then the (m + n)th term is:
An eight digit number divisible by $9$ is to be formed by using $8$ digits out of the digits $0,1,\ldots,9$ without replacement.
The number of ways in which this can be done is
Sum of digits must be divisible by $9$.
Total sum of digits $0$ to $9$ is $45$.
Choose $8$ digits such that their sum is divisible by $9$.
Possible digit-exclusions give $4$ valid cases.
Arrangements of remaining $8$ digits excluding leading zero restriction gives
$4\times7!$
Answer: $\boxed{4(7!)}$
$7\equiv2\pmod5$
So
$7^k\equiv2^k\pmod5$
$2^k\pmod5$ cycles as $2,4,3,1$ (period $4$).
$7^m+7^n\equiv0\pmod5$ when residues are complementary.
Total valid ordered pairs $=2500$
Answer: $\boxed{2500}$
A and B are independent witness in a case. The chance that A speaks truth is x and B speaks
truth is y. If A and B agree on certain statement, the probability that the statement is true is
The average marks per student in a class of 30 students were 45. On rechecking it was found that marks had been entered wrongly in two cases. After correction these marks were increased by 24 and 34 in the two cases. The correct average marks per student are
If $a,b,c$ are the roots of the equation
$x^3-3px^2+3qx-1=0$,
then the centroid of the triangle with vertices
$\left(a,\frac1a\right),\left(b,\frac1b\right),\left(c,\frac1c\right)$
is the point
Centroid $=\left(\dfrac{a+b+c}{3},\dfrac{\frac1a+\frac1b+\frac1c}{3}\right)$
From the equation,
$a+b+c=3p$
Also
$\dfrac1a+\dfrac1b+\dfrac1c=\dfrac{ab+bc+ca}{abc}=\dfrac{3q}{1}=3q$
Hence centroid $=(p,q)$
Answer: $\boxed{(p,q)}$
Given: Harmonic mean is 4:
$$\frac{2ab}{a + b} = 4 \quad \text{(1)}$$
Arithmetic mean \( A = \frac{a + b}{2} \),
Geometric mean \( G = \sqrt{ab} \)
Given:
$$2A + G^2 = 27$$
$$2 \cdot \frac{a + b}{2} + ab = 27 \Rightarrow a + b + ab = 27 \quad \text{(2)}$$
From (1): Multiply both sides by \( a + b \):
$$2ab = 4(a + b) \Rightarrow ab = 2(a + b) \quad \text{(3)}$$
Substitute (3) into (2):
$$a + b + 2(a + b) = 27 \Rightarrow 3(a + b) = 27 \Rightarrow a + b = 9$$
Then from (3):
$$ab = 2 \cdot 9 = 18$$
Now solve:
$$x^2 - (a + b)x + ab = 0 \Rightarrow x^2 - 9x + 18 = 0$$
$$\Rightarrow x = 3, 6$$
Final Answer:
$$\boxed{3 \text{ and } 6}$$
Consider the matrix $$B=\begin{pmatrix}{-1} & {-1} & {2} \\ {0} & {-1} & {-1} \\ {0} & {0} & {-1}\end{pmatrix}$$. The sum of all the entries of the matrix $B^{19}$ is
The value of ‘a’ for which the system of equations
$a^3 x + (a+1)^3 y + (a+2)^3 z = 0$
$ax + (a+1) y + (a+2) z = 0$
$x + y + z = 0$
has a non–zero solution, is
For non-zero solution, determinant must be zero.
Matrix:
$\begin{vmatrix}
a^3 & (a+1)^3 & (a+2)^3 \
a & a+1 & a+2 \
1 & 1 & 1
\end{vmatrix} = 0$
Factor out structure:
This determinant becomes zero when columns become linearly dependent → when $a=-1$ or $a=0$ or $a=1$.
Checking each value in equations:
• $a = -1$ → valid
• $a = 0$ → equations collapse but still allow nonzero solution
• $a = 1$ → also gives dependence
But only one of these matches the options where system definitely has non-zero solution.
Correct value = $-1$
Let tangent be $y=mx+c$, $m>0$.
Tangency with $y^2=4x$ gives $c=\dfrac1m$.
Tangency with the circle gives $|3m-c|=3\sqrt{m^2+1}$.
Solving gives $m=\dfrac1{\sqrt3},\ c=\sqrt3$.
Equation:
$\sqrt3y=x+3$
Answer: $\boxed{\sqrt3y=x+3}$
In an entrance test there are multiple choice questions, with four possible answer to each question of which one is correct. The probability that a student knows the answer to a question is 90%. If the student gets the correct answer to a question, then the probability that he as guessing is
Let $\vec{a}=2\widehat{i}\, +\widehat{j}\, +2\widehat{k}$ , $\vec{b}=\widehat{i}-\widehat{j}+2\widehat{k}$ and $\vec{c}=\widehat{i}+\widehat{j}-2\widehat{k}$ are are three vectors. Then, a vector in the plane of $\vec{a}$ and $\vec{c}$ whose projection on $\vec{b}$ is of magnitude $\frac{1}{\sqrt{6}}$ is
Let $f: R \rightarrow R$ be defined by $f(x) = \begin{cases} x + 2 & \text{if } x < 0 \\ |x - 2| & \text{if } x \geq 0 \end{cases}$. Find $\int_{-2}^{3} f(x)\, dx$
A man is known to speak the truth 2 out of 3 times. He threw a dice cube with 1 to 6 on its faces and reports that it is 1. Then the probability that it is actually 1 is
The scores of students in a national level examination are normally distributed with a mean of 500 and a standard deviation of 100. If the value of the cumulative distribution of the standard normal random variable at 0.5 is 0.691, then the probability that a randomly selected student scored between 450 and 500 is
A letter is taken at random from the letters of the word STATISTICS and another letter is taken at random from the letters of the word ASSISTANT.
The probability that they are the same letter is
Let A and B be two square matrices of same order satisfying $A^2+5A+5I =0$ and $B^2+3B+I=0$ repectively. Where I is the identity matrix. Then the inverse of the matrix $C= BA+2B+2A+4I$ is
If $a \ne p$, $b \ne q$, $c \ne r$ and
$\left|\begin{matrix}
p & b & c \\
a & q & c \\
a & b & r
\end{matrix}\right| = 0$,
then the value of $\frac{p}{p-a} + \frac{q}{q-b} + \frac{r}{r-c}$ is
Solution:
Given
$\left|\begin{matrix}
p & b & c \\
a & q & c \\
a & b & r
\end{matrix}\right| = 0,$
the rows are linearly dependent.
Using the determinant identity, we get
$\frac{p}{p-a} + \frac{q}{q-b} + \frac{r}{r-c} = 1.$
A bag contains $6$ red and $4$ green balls.
A fair die is rolled and a number of balls equal to that appearing on the die is chosen from the bag at random.
The probability that all the balls selected are red is
The captains of five cricket teams, including India and Australia, are lined up randomly
next to one other for a group photo. What is the probability that the captains of India and
Australia will stand next to each other?
Treat India–Australia as one block. Then we have $4!$ ways to arrange the block with the other 3 captains, and $2$ orders inside the block (IA or AI). Favorable $=2\cdot4!=48$; total $=5!=120$.
If $\omega \ne 1$ is a cube root of unity and $i = \sqrt{-1}$, the value of the determinant
$\left|\begin{matrix}
1 & 1+i+\omega^2 & \omega \\
1-i & -1 & \omega^2 - 1 \\
-i & -i+\omega-1 & -\omega^3
\end{matrix}\right|$
is
Solution:
Using $\omega^3 = 1$ and $\omega^2 + \omega + 1 = 0,$ simplify the entries.
After row/column reduction and applying cube root identities, the determinant becomes
$\omega^2.$
The value of $\lambda$ for which the volume of the parallelepiped formed by the vectors
$\vec i+\lambda\vec j+\vec k,\ \vec j+\lambda\vec k,\ \lambda\vec i+\vec k$
is minimum is
If the position vector of A and B relative to O be $\widehat{i}\, -4\widehat{j}+3\widehat{k}$ and $-\widehat{i}\, +2\widehat{j}-\widehat{k}$ respectively, then the median through O of ΔABC is:
The point $(4,1)$ undergoes the following transformations successively:
(i) Reflection about the line $y=x$
(ii) Translation through a distance $2$ units along the positive $x$-axis
(iii) Rotation by an angle $\frac{\pi}{4}$ anticlockwise about the origin
The final position of the point is:
Solution:
Step 1: Reflect (4,1) about y=x → (1,4)
Step 2: Translate 2 units in +x direction → (1+2, 4) = (3,4)
Step 3: Rotate (3,4) by π/4 anticlockwise:
New x = (3 - 4)/√2 = -1/√2
New y = (3 + 4)/√2 = 7/√2
Final point = $\left(\frac{-1}{\sqrt{2}}, \frac{7}{\sqrt{2}}\right)$
A six-faced die is a biased one. It is thrice more likely to show an odd number than to show an even number. It is thrown twice. The probability that the sum of the numbers in the two throws is even is
Let $P(\text{even})=p$ and $P(\text{odd})=3p$
$p+3p=1 \Rightarrow p=\dfrac14$
So
$P(\text{even})=\dfrac14,\quad P(\text{odd})=\dfrac34$
Sum is even when both outcomes are even or both are odd.
$P=\left(\dfrac14\right)^2+\left(\dfrac34\right)^2=\dfrac1{16}+\dfrac9{16}=\dfrac{10}{16}=\dfrac58$
Answer: $\boxed{\dfrac58}$
There are two coins, say blue and red. For blue coin, probability of getting head is 0.99 and
for red coin, it is 0.01. One coin is chosen randomly and is tossed. The probability of getting
head is
If the two pair of lines $X^2 - 2mXY - Y^2 = 0$ and $X^2 - 2nXY - Y^2 = 0$ are such that one represents the bisector of the angles between the other, then:
A letter is known to have come from either TATANAGAR or CALCUTTA. On the envelope, just two consecutive letters, TA, are visible. The probability that the letter has come from CALCUTTA is
TATANAGAR has $2$ occurrences of TA
CALCUTTA has $3$ occurrences of TA
Total occurrences $=5$
Required probability
$=\dfrac{3}{5}$
This is not listed.
Answer: $\boxed{\text{None of these}}$
If altitudes of a triangle are in HP then its side will be in AP because sides are inverse proportion to height as area is constant. a, b, c are sides of triangle.
The area of the triangle formed by the vertices whose position vectors are $3\widehat{i}+\widehat{j}$ , $5\widehat{i}+2\widehat{j}+\widehat{k}$ , $\widehat{i}-2\widehat{j}+3\widehat{k}$ is
If $\cos\alpha+\cos\beta=a$, $\sin\alpha+\sin\beta=b$ and $\theta$ is the arithmetic mean between $\alpha$ and $\beta$, then
$\sin2\theta+\cos2\theta$ is equal to
Using identity
$(1+\tan\theta)(1+\tan(45^\circ-\theta))=2$
There are $22$ such pairs from $1^\circ$ to $44^\circ$ and
$(1+\tan45^\circ)=2$
So
$2^{22}\times2=2^{23}$
Hence $n=23$
Answer: $\boxed{23}$
If $\vec{a}, \vec{b}$ and $\vec{c} $ are three vectors such that $\vec{a} \times \vec{b}=\vec{c}$ , $\vec{a}.\vec{c} = 2$ and $\vec{b}.\vec{c} = 1$. If $|\vec{b}| = 1$, then the value of $|\vec{a}| $ is
This is possible only if $\vec{c}$ is not perpendicular to $\vec{a}$, meaning $\vec{c}$ is not just $\vec{a} \times \vec{b}$ but also has a component along $\vec{a}$.
Use the identity:
$(\vec{a} \times \vec{b}) \cdot \vec{c}
= \det(\vec{a},\vec{b},\vec{c})$
But we need magnitudes.
Take dot product of $\vec{b}$ with $\vec{c}$:
Three positive number whose sum is 21 are in arithmetic progression. If 2, 2, 14 are added to them respectively then resulting numbers are in geometric progression. Then which of the following is not among the three numbers?
If $f\colon R\rightarrow R$ is defined by $f(x)=\begin{cases}{\frac{x+2}{{x}^2+3x+2}} & {,\, if\, x\, \in R-\{-1,-2\}} \\ {-1} & {,if\, x=-2} \\ {0} & {,if\, x=-1}\end{cases}$ , then f(x) is continuous on the set
If x, y and z are three cube roots of 27, then the determinant of the matrix $\begin{bmatrix}{x} & {y} & {z} \\ {y} & {z} & {x} \\ {z} & {x} & {y}\end{bmatrix}$ is
If $x, y, z$ are three cube roots of $27$, then the determinant of the matrix
\[
\begin{pmatrix}
x & y & z\\[4pt]
y & z & x\\[4pt]
z & x & y
\end{pmatrix}
\]
is:
The cube roots of $27 = 3^3$ are:
\[
x = 3,\qquad y = 3\omega,\qquad z = 3\omega^2,
\]
where $\omega$ is a cube root of unity satisfying
\[
\omega^3 = 1,\qquad 1+\omega+\omega^2 = 0.
\]
For a circulant matrix, the determinant is:
\[
(x+y+z)(x+\omega y+\omega^2 z)(x+\omega^2 y+\omega z).
\]
Now compute the first factor:
\[
x+y+z = 3(1+\omega+\omega^2) = 3\cdot 0 = 0.
\]
Therefore,
\[
\det = 0.
\]
The value of $\lambda$ such that the four points whose position vectors are
$3\vec i-2\vec j+\lambda\vec k,\ 6\vec i+3\vec j+\vec k,\ 5\vec i+7\vec j+3\vec k$ and $2\vec i+2\vec j+6\vec k$
are coplanar is
Four points are coplanar if the determinant of their position vectors (relative to one point) is zero.
After forming vectors and evaluating the determinant, we get
$\lambda=4$
Answer: $\boxed{4}$
If the tangents at the extremities of a focal chord of the parabola $x^2 = 4ay$ meet at a point where the abscissas are $x_1$ and $x_2$, then
$x_1 x_2 =$
Parametric form of parabola: x = 2at, y = at²
Focal chord endpoints: t and –1/t
Slope of tangent at t: 1/t
Equation of tangent meets the tangent at –1/t
Product of x-intercepts = a²
Let $\vec A=2\vec i+\vec j-2\vec k$ and $\vec B=\vec i+\vec j$.
If $\vec C$ is a vector such that
$\vec A\cdot\vec C=|\vec C|$,
$|\vec C-\vec A|=2\sqrt2$
and the angle between $\vec A\times\vec B$ and $\vec C$ is $30^\circ$,
then $|(\vec A\times\vec B)\times\vec C|$ is equal to
The probability of occurrence of two events E and F are 0.25 and 0.50, respectively. the probability of their simultaneous occurrence is 0.14. the probability that neither E nor F occur is
Let $\vec{a}$, $\vec{b}$ and $\vec{c}$ be unit vectors such that the angle between them is ${\cos }^{-1}\Bigg{\{}\frac{1}{4}\Bigg{\}}$. If $\vec{b}=2\vec{c}+\lambda \vec{a}$,
where $\lambda$ > 0 and $\vec{b}=4$, then $\lambda$ is equal to
A rigid body is rotating at the rate of $3$ radians per second about an axis $AB$, where
$A(1,-2,1)$ and $B(3,-4,2)$.
The velocity of the point $P(5,-1,-1)$ of the body is
Direction vector of axis
$\vec{AB}=(2,-2,1)$
Unit vector along axis
$\hat n=\dfrac{(2,-2,1)}{3}$
Angular velocity
$\vec\omega=3\hat n=(2,-2,1)$
Position vector of $P$ relative to $A$:
$\vec r=(4,1,-2)$
Velocity
$\vec v=\vec\omega\times\vec r=3\vec i+8\vec j+10\vec k$
A tower subtends angles $\alpha, 2\alpha$ and $3\alpha$ respectively at points A, B and C which are lying on a horizontal line through the foot of the tower. Then $\frac{AB}{BC}$ is equal to
Solution:
lim_{x→0} x·sin(1/x) = 0
⇒ f is continuous at 0.
f'(0) = lim_{x→0} [x sin(1/x)]/x = sin(1/x)
But sin(1/x) has no limit as x→0⁺ or x→0⁻.
⇒ Both f'(0+) and f'(0-) do not exist.
First off all select 5 boxes out 6 boxes in which 5 big ball can fit then arrange these ball in these 5 boxes and then put remaining 4 ball in any remaining box.
In a triangle, if the sum of two sides is x and their product is y such that (x+z)(x-z)=y, where z is the third side of the triangle , then triangle is
If $\vec{a}=\hat{i}+\hat{j}+\hat{k}$, $\vec{b}=2\hat{i}-\hat{j}+3\hat{k}$ and $\vec{c}=\hat{i}-2\hat{j}+\hat{k}$, then a vector of magnitude $\sqrt{22}$ which is parallel to $2\vec{a}-\vec{b}+3\vec{c}$ is
Step 1: Convert HP to AP
Since $a, H_1, H_2, \ldots, H_n, b$ is in HP,
$\dfrac{1}{a},\ \dfrac{1}{H_1},\ \ldots,\ \dfrac{1}{H_n},\ \dfrac{1}{b}$ is in AP with $n+2$ terms.
Consider the sample space $\Omega={\{(x,y):x,y\in{\{1,2,3,4\}\}}}$ where each outcome is equally likely.
Let A = {x ≥ 2} and B = {y > x} be two events. Then which of the following is NOT true?
A student council has 10 members. From this one President, one Vice-President, one Secretary, one Joint-Secretary and two Executive Committee members have to be elected. In how many ways this can be done?
Let the line $\frac{x}{4}+\frac{y}{2}=1$ meets the x-axis and y-axis at A and B, respectively. M is the midpoint
of side AB, and M' is the image of the point M across the line x + y = 1. Let the point P lie on
the line x + y = 1 such that the $\Delta$ABP is an isosceles triangle with AP = BP. Then the
distance between M' and P is
In a survey where 100 students reported which subject they like, 32 students in total liked Mathematics, 38 students liked Business and 30 students liked Literature. Moreover, 7 students liked both Mathematics and Literature, 10 students liked both Mathematics and Business. 8 students like both Business and Literature, 5 students liked all three subjects. Then the number of people who liked exactly one subject is
Which one of the following is NOT a correct statement?
The value of standard deviation changes by a change of scale The standard deviation is greater than or equal to the mean deviation (about mean) The sum of squares of deviations is minimum when taken from the mean The variance is expressed in the same units as the units of observation Go to Discussion MCA NIMCET Previous Year PYQMCA NIMCET NIMCET 2025 PYQ
Solution
Question: Which one of the following is NOT a correct statement?
The value of standard deviation changes by a change of scale.
The standard deviation is greater than or equal to the mean deviation (about mean).
The sum of squares of deviations is minimum when taken from the mean.
The variance is expressed in the same units as the units of observation.
Answer:Option 4
Why: Variance has squared units, not the same units as the data (e.g., if data are in cm, variance is in cm²). Standard deviation (the square root of variance) has the same units as the data.
Notes:
Change of scale: if each value is multiplied by \(k\), then \(\text{SD}\) becomes \(|k|\cdot \text{SD}\) and \(\text{Var}\) becomes \(k^2\cdot \text{Var}\).
\(\text{SD} \ge \text{Mean Deviation (about mean)}\) is a standard inequality.
\(\sum (x_i - a)^2\) is minimized at \(a = \bar{x}\) (the mean).
An equilateral triangle is inscribed in the parabola $y^2 = x$. One vertex of the triangle is at
the vertex of the parabola. The centroid of triangle is
The vectors $\vec{a},\vec{b},\vec{c}$ are equal in length and taken pairwise make equal angles.
If $\vec{a}=\hat{i}+\hat{j}$, $\vec{b}=\hat{j}+\hat{k}$ and $\vec{c}$ makes an obtuse angle with $\hat{i}$, then $\vec{c}$ is equal to
Equal lengths and equal pairwise angles ⇒ vectors form a symmetric set.
Dot-products must satisfy:
$\vec{a}\cdot\vec{b}=\vec{b}\cdot\vec{c}=\vec{c}\cdot\vec{a}$
Also $\vec{c}$ must make obtuse angle with $\hat{i}$ ⇒ its $i$-component < 0.
Solving gives:
$\vec{c}=\frac{1}{3}\hat{i}+\frac{4}{3}\hat{j}-\frac{1}{3}\hat{k}$
The angles of depression of the top and bottom of an 8m tall building from the top of a multi storied building are 30° and 45°, respectively. What is the height of the multistoried building
and the distance between the two buildings?
The position vectors of $A,B,C,D$ are
$\hat{i}+\hat{j}+\hat{k}$,
$2\hat{i}+5\hat{j}$,
$3\hat{i}+2\hat{j}-3\hat{k}$,
$\hat{i}-6\hat{j}-\hat{k}$
Angle between $\overrightarrow{AB}$ and $\overrightarrow{CD}$ is:
The number of accidents per week in a town follows Poisson distribution with mean 3 (In Exam Given 2, which is incorrect).
If the probability that there are three accidents in two weeks time is $ke^{-6}$, then the
value of k is
Let $\vec{a},\vec{b},\vec{c}$ be three non-zero vectors, no two collinear.
If $\vec{a}+\vec{b}$ is collinear with $\vec{c}$ and $\vec{b}+\vec{c}$ is collinear with $\vec{a}$, then $\vec{a}+\vec{b}+\vec{c}$ is equal to
Conditions:
$\vec{a}+\vec{b}=\lambda\vec{c}$
$\vec{b}+\vec{c}=\mu\vec{a}$
Solving gives:
$\vec{a}+\vec{b}+\vec{c}=0$
Which is none of the given vectors.
The lines $px+qy=1$ and $qx+py=1$ are respectively the sides AB, AC of the triangle ABC and the base BC is bisected at $(p,q)$. Equation of the median of the triangle through the vertex A is
Let $\alpha$ and $\beta$ be the roots of the equation $x^2 - px + r = 0$ and $\dfrac{\alpha}{2}, \beta$ are the roots of the equation $x^2 - ax + r = 0$, then the value of $r$,
If the graph of y = (x – 2)2 – 3 is shifted by 5 units up along y-axis and 2 units to the right along
the x-axis, then the equation of the resultant graph is
If the vectors $a\hat{i}+\hat{j}+\hat{k},\hat{i}+b\hat{j}+\hat{k},\hat{i}+\hat{j}+c\hat{k}$ , $(a,b,c\ne1)$ are coplanar, then $\frac{1}{1-a}+\frac{1}{1-b}+\frac{1}{1-c}=$
Let $F_1, F_2$ be foci of hyperbola $\frac{{x}^2}{{a}^2}-\frac{{y}^2}{{b}^2}=1$, a>0, b>0, and let O be the origin. Let M be an arbitrary point on curve C and above X-axis and H be a
point on $MF_1$ such that $MF_2\perp{{F}}_1{{F}}_2$, $MF_1\perp{{O}}{{H}}$, $|OH|=\lambda |OF_2|$ with $\lambda \in(2/5, 3/5)$, then the range of the eccentricity $e$ is
$\cos 20^\circ(\sqrt{3}-4)$ is negative because $(\sqrt{3}-4)<0$.
Compute approximate:
$\cos20^\circ \approx 0.94$
$\sqrt{3}-4 \approx -2.268$
Product ≈ $-2.13$
Which is none of the options 1, -1, 0.
The number of different license plates that can be formed in the format 3 English letters (A….Z)
followed by 4 digits (0, 1, …9) with repetitions allowed in letters and digits is equal to
Let $\vec{a}=\hat{i}+\hat{j}$ and $\vec{b}=2\hat{i}-\hat{k}$, the point of intersection of the lines $\vec{r}\times\vec{a}=\vec{b}\times\vec{a}$ and $\vec{r}\times\vec{b}=\vec{a}\times\vec{b}$ is
A password consists of two alphabets from English followed by three numbers chosen from 0 to 3.
If repetitions are allowed, the number of different passwords is
If $\alpha$ and $\beta$ are the two roots of the quadratic equation $x^2 + ax + b = 0, (ab \ne 0)$ then the quadratic roots whose roots $\frac{1}{\alpha^3+\alpha}$ and $\frac{1}{\beta^3+\beta}$ is
Given $x^{2} + ax + b = 0$ with roots $\alpha,\beta$,
we use
$\alpha + \beta = -a$ and $\alpha\beta = b$.
Required new roots are
$\dfrac{1}{\alpha^{3}+\alpha}$ and $\dfrac{1}{\beta^{3}+\beta}$.
Since
$\alpha^{3}+\alpha = \alpha(\alpha^{2}+1)$
and using $\alpha^{2}=-a\alpha-b$ (and same for $\beta$),
after simplification the sum and product of new roots become:
If $\vec{a}$, $\vec{b}$ and $\vec{c}$ are vectors such that $\vec{a}$+$\vec{b}$+$\vec{c}$ = 0 and |$\vec{a}$| =7, $\vec{b}$=5, |$\vec{c}$| = 3, then the angle between the vectors $\vec{b}$ and $\vec{c}$
An equilateral triangle is inscribed in the parabola $y^{2} = 4ax$, such that one of the vertices of the triangle
coincides with the vertex of the parabola. The length of the side of the triangle is:
The rate of increase of length of the shadow of a man $2$ meters high, due to a lamp at $10$ meters height, when he is moving away from it at $2 \text{ m/sec}$ is
A chain of video stores sells three different brands of DVD players. Of its DVD player sales, 50% are
brand 1, 30% are brand 2 and 20% are brand 3. Each manufacturer offers one year warranty on parts
and labor. It is known that 25% of brand 1 DVD players require warranty repair work whereas the corresponding
percentage for brands 2 and 3 are 20% and 10% respectively. The probability that a randomly selected purchaser
has a DVD player that will need repair while under warranty, is:
Let $\mathbb{R}\rightarrow\mathbb{R}$ be any function defined as $f(x)=\begin{cases}{{x}^{\alpha}\sin \frac{1}{{x}^{\beta}}} & {,x\ne0} \\ {0} & {,x=0}\end{cases}$, $\alpha , \beta \in \mathbb{R}$. Which of the following is true? ($\mathbb{R}$ denotes the set of all real numbers)
$f(x)$ is continuous at x = 0 for all $\alpha{\gt}0\,$ and $\beta\in\mathbb{R}$ $f(x)$ is continuous at x = 0, for all $\alpha $ and$ \beta\in\mathbb{R}$ $f(x)$ is continuous at x = 10 for only $\alpha{\gt}0\,$ and $\beta >0$ $f(x)$ is differentiable at $x=0$ for all $\alpha{\gt}0\, $and $\beta >0$ Go to Discussion MCA NIMCET Previous Year PYQMCA NIMCET NIMCET 2025 PYQ
Solution
The function is
$f(x) = x^{\alpha}\sin\left(\dfrac{1}{x^{\beta}}\right)$ for $x \ne 0$,
and $f(0)=0$.
To check continuity at $x=0$, consider:
$\displaystyle \lim_{x\to 0} x^{\alpha}\sin\left(\frac{1}{x^{\beta}}\right)$.
A person stands at a point $A$ due south of a tower and observes elevation $60^\circ$.
He walks west to $B$, elevation becomes $45^\circ$.
At point $C$ on $AB$ extended, elevation becomes $30^\circ$.
Find $\dfrac{AB}{BC}$.
The locus of the intersection of the two lines $\sqrt{3} x-y=4k\sqrt{3}$ and $k(\sqrt{3}x+y)=4\sqrt{3}$, for different
values of k, is a hyperbola. The eccentricity of the hyperbola is:
Constant forces $\vec{P}= 2\hat{i} - 5\hat{j} + 6\hat{k} $ and $\vec{Q}= -\hat{i} + 2\hat{j}- \hat{k}$ act on a particle. The work done when the particle is
displaced from A whose position vector is $4\hat{i} - 3\hat{j} - 2\hat{k} $, to B whose position vector is $6\hat{i} + \hat{j} - 3k\hat{k}$ , is:
Suppose $A_1,A_2,\ldots,A_{30}$ are 30 sets each with five elements and $B_1,B_2,B_3,\ldots,B_n$ are n sets (each with three elements) such that $\bigcup ^{30}_{i=1}{{A}}_i={{\bigcup }}^n_{j=1}{{B}}_i=S\, $ and each element of S belongs to exactly ten of the $A_i$'s and exactly 9 of the $B^{\prime}_j$'s. Then $n=$
Count incidences via the \(A_i\): There are 30 sets each of size 5, so total memberships \(=30\times 5=150\). Each element of \(S\) lies in exactly 10 of the \(A_i\), so also \(= m\times 10\). Hence \(m=\dfrac{150}{10}=15\).
Count incidences via the \(B_j\): There are \(n\) sets each of size 3, so total memberships \(=n\times 3\). Each element of \(S\) lies in exactly 9 of the \(B_j\), so also \(= m\times 9 = 15\times 9=135\).
The circle $x^2 + y^2+ \alpha x+ \beta y+ \gamma=0$ is the image of the circle $x^2 + y^2- 6x- 10y+ 30=0$ across
the line 3x + y = 2. The value of $[\alpha+ \beta+ \gamma]$ is (where [.] represents the floor function.)
If $\vec{a}, \vec{b}$ and $\vec{c}$ are unit vectors, then $|\mathbf{a} - \mathbf{b}|^2 + |\mathbf{b} - \mathbf{c}|^2 + |\mathbf{c} - \mathbf{a}|^2$ does not exceeds
The vector $\vec{a} = \alpha\hat{i} + 2\hat{j} + \beta\hat{k}$ lies in the plane of the vector $\vec{b} = \hat{i} + \hat{j}$ and $\vec{c} = \hat{j} + \hat{k}$ and bisects the angle between $\vec{b}$ and $\vec{c}$. Then which of the following gives possible values of $\alpha$ and $\beta$?
\begin{enumerate}
For the vectors $\vec{a}=-4\hat{i}+2\hat{j}, \vec{b}=2\hat{i}+\hat{j}$ and $\vec{c}=2\hat{i}+3\hat{j}$, if $\vec{c}=m\vec{a}+n\vec{b}$ then the value of m + n is
Forces $4\hat{i} - 3\hat{j} + 7\hat{k}$ and $-2\hat{i} + 2\hat{j} - 8\hat{k}$ are acting on a particle and displaced it from the point $(5, 7, 1)$ to $(2, 5, -6)$, then the work done by the force is
The probability that a man who is x years old will die in a year is p. Then, amongst n persons $A_1,A_2,\ldots A_n$ each x year old now, the probability that ${{A}}_1$ will die in one year and (be the first to die ) is
A bird is flying in a straight line with velocity vector 10i+6j+k, measured in km/hr. If the starting point is (1,2,3), how much time does it to take to reach a point in space that is 13m high from the ground?
m distinct animals of a circus have to be placed in m cages, one is each cage. There are n small
cages and p large animal (n < p < m). The large animals are so large that they do not fit in small
cage. However, small animals can be put in any cage. The number of putting the animals into
cage is
Angle between $\vec{a}$ and $\vec{b}$ is $120{^{\circ}}$. If $|\vec{b}|=2|\vec{a}|$ and the vectors , $\vec{a}+x\vec{b}$ , $\vec{a}-\vec{b}$ are at right angle, then $x=$
Let $g:\mathbb{R}\rightarrow \mathbb{R}$ and $h:\mathbb{R}\rightarrow \mathbb{R}$, be two functions such that $h(x) = sgn(g(x))$. Then select
which of the following is not true?( $\mathbb{R}$ denotes the set of all real numbers, sgn stands for
signum function)
1) "The domain of $h(x)$ is the same as the domain of $g(x)$."
$\Rightarrow$ True, because $\operatorname{sgn}(g(x))$ is defined for every $x$ where $g(x)$ is defined.
2) "The domain of continuity of $h(x)$ equals the domain of continuity of $g(x) - \{x\in\mathbb{R} : g(x)=0\}$."
At points where $g(x)\neq 0$, $h(x)$ is locally constant ($1$ or $-1$), hence continuous there (provided $g$ itself is continuous).
At points where $g(x)=0$, $h(x)$ jumps from $-1$ to $1$, so it is discontinuous.
$\Rightarrow$
This statement is true.
3) "The domain of $h(x)$ is different from the domain of $g(x)$ at the same point."
Since for every $x$ in the domain of $g$, $h(x)=\operatorname{sgn}(g(x))$ is defined, the domains are exactly the same; they never differ.
$\Rightarrow$ This statement is false.
4) " $h(x)$ is discontinuous at $g(x)=0$."
At any $x_0$ where $g(x_0)=0$, the left and right limits of $h(x)$ are $-1$ and $1$, not equal to $h(x_0)=0$.
$\Rightarrow$ $h$ is discontinuous there, so this statement is true.
Therefore, the statement which is **not true** is:
$\boxed{\text{Option 3}}$
The slope of the function \[
f(x) =
\begin{cases}
x^2 \sin\!\left(\dfrac{1}{x}\right), & \text{if } x \ne 0, \\[8pt]
0, & \text{if } x = 0
\end{cases}
\]
An airplane, when 4000m high from the ground, passes vertically above another airplane at
an instant when the angles of elevation of the two airplanes from the same point on the
ground are 60° and 30°, respectively. Find the vertical distance between the two airplanes.
In a group of 200 students, the mean and the standard deviation of scores were found to be 40 and 15,
respectively. Later on it was found that the two scores 43 and 35 were misread as 34 and 53, respectively. The corrected mean of scores is:
Suppose $t_1, t_2, ...t_5$ are in AP such that $\sum ^{18}_{l=0}{{t}}_{3l+1}=1197$ and ${{t}}_7+{{3}}t_{22}=174$. If $\sum ^9_{l=1}{{{t}}_l}^2=947b$, then the value of $b$ is
Through any point (x, y) of a curve which passes through the origin, lines are drawn parallel to the coordinate axes. The curve, given that it divides the rectangle formed by the two lines and the axes into two areas, one of which is twice the other, represents a family of
If $A=\begin{bmatrix} a &b &c \\ b & c & a\\ c& a &b \end{bmatrix}$ , where $a, b, c$ are real positive numbers such that $abc = 1$ and $A^{T}A=I$ then
the equation that not holds true among the following is
If $\vec{e_1}=(1,1,1)$ and $\vec{e_2}=(1,1,-1)$ and $\vec{a}$ and $\vec{b}$ and two vectors such that $\vec{e_2}=\vec{a}+2\vec{b}$ , then angle between $\vec{a}$ and $\vec{b}$
Since
$P(E|F) = \dfrac{P(E \cap F)}{P(F)}$,
the condition becomes:
$P(E)P(F) = P(E \cap F)$,
which is exactly the definition of independence of $E$ and $F$.
Now check each option:
1) "E and F are independent"
→ This is exactly equivalent to $P(E)=P(E|F)$ (TRUE).
3) $P(F) = P(F|E)$
→ Also true under independence (TRUE).
4) $E^c$ and $F$ are independent
→ Independence is preserved under complements (TRUE).
2) $2P(E^c)P(F^c) \ne P(E \cap F^c)$
→ This statement has no relation to $P(E)=P(E|F)$ and does NOT follow from independence (NOT equivalent).
Therefore, the option that is NOT equivalent is:
Option 2.
A line passing through (4, 2) meets the x and y-axis at P and Q respectively. If O is the origin, then the locus of the centre of the circumcircle of ΔOPQ is -
If $\alpha$ and $\beta$ are the roots of the equation $2x^{2}+ 2px + p^{2} = 0$, where $p$ is a non-zero real number, and $\alpha^{4}$ and $\beta^{4}$ are the roots of $x^{2} - rx + s = 0$, then the roots of $2x^{2} - 4p^{2}x + 4p^{4} - 2r = 0$ are:
In a class of 50 students, it was found that 30
students read "Hitava", 35 students read "Hindustan" and 10 read neither. How many
students read both: "Hitavad" and "Hindustan" newspapers?
The foci of the ellipse $\frac{x^{2}}{16}+\frac{y^{2}}{b^{2}}=1$ and the hyperbola $\frac{x^{2}}{144}-\frac{y^{2}}{{81}}=\frac{1}{25}$ coincide, then the value of $b^{2}$ is
A tower subtends an angle of 30° at a point on the same level as the foot of the tower. At a
second point h meters above the first, the depression of the foot of the tower is 60°. What is
the horizontal distance of the tower from the point?
There are 40 female and 20 male students in a class. If the average heights of female and
male students are 5.15 feet and 5.66 feet, respectively, then the average height (in feet)
of all the students in the class equals
If $\vec{A}=4\hat{i}+3\hat{j}+\hat{k}$ and $\vec{B}=2\hat{i}-\hat{j}+2\hat{k}$ , then the unit vector $\hat{N}$ perpendicular to the vectors $\vec{A}$ and $\vec{B}$ ,such that $\vec{A}, \vec{B}$ , and $\hat{N}$ form a right handed system, is:
The sum of two vectors $\vec{a}$ and $\vec{b}$ is a vector $\vec{c}$ such that $|\vec{a}|=|\vec{b}|=|\vec{c}|=2$. Then, the magnitude of $\vec{a}-\vec{b}$ is equal to:
$2 \in A \cup B$ implies that if $2 \notin A$ then $2 \in B$ ${2,3} \subseteq A$ implies that $2 \in A$ and $3 \in A$ $A \cap B \supseteq {2,3}$ implies that ${2,3} \subseteq A$ and ${2,3} \subseteq B$ none of the above Go to Discussion MCA NIMCET Previous Year PYQMCA NIMCET NIMCET 2016 PYQ
There is a young boy’s birthday party in which 3
friends have attended. The mother has arranged 10
games where a prize is awarded for a winning game.
The prizes are identical. If each of the 4 children
receives at least one prize, then how many
distributions of prizes are possible?
The value of the sum $\frac{1}{2\sqrt{1}+1\sqrt{2}}+\frac{1}{3\sqrt{2}+2\sqrt{3}}+\frac{1}{4\sqrt{3}+3\sqrt{4}}+...+\frac{1}{25\sqrt{24}+24\sqrt{25}}$ is
If $\vec{a}=\hat{i}-\hat{k},\, \vec{b}=x\hat{i}+\hat{j}+(1-x)\hat{k}$ and $\vec{c}=y\hat{i}+x\hat{j}+(1+x-y)\hat{k}$ , then $[\vec{a} , \vec{b}, \vec{c}]$ depends on
From three collinear points A, B and C on a level ground, which are on the same side of a tower, the angles of elevation of the top of the tower are 30°, 45° and 60° respectively. If BC = 60 m, then AB is:
A problem in Mathematics is given to 3 students A, B, and C. If the probability of A solving the problem is 1/2
and B not solving it is 1/4
. The whole probability of the problem being solved is 63/64
, then what is the probability of solving it by C?
A and B play a game where each is asked to select a number from 1 to 25. If the two numbers match, both win a prize. The probability that they will not win a prize in a single trial is
If
$A = \begin{bmatrix} \cos\alpha & \sin\alpha \\ -\sin\alpha & \cos\alpha \end{bmatrix},$
then for any positive integer $n$, $A^n$ is
$$
\begin{bmatrix} sinn \alpha & cosn \alpha \\ cosn \alpha & -sinn \alpha \end{bmatrix}
\quad
$$ $$
\begin{bmatrix} cos n \alpha & sin n \alpha \\ sin n \alpha & cos n \alpha \end{bmatrix}
\quad
$$ $$ \begin{bmatrix} cos nn \alpha & sinn \alpha \\ sinn \alpha & -cosn \alpha \end{bmatrix} \quad $$ $$ \begin{bmatrix} cos nn \alpha & sinn \alpha \\ -sinn \alpha & cosn \alpha \end{bmatrix} \quad $$
If the foci of the ellipse $b^{2}x^{2}+16y^{2}=16b^{2}$ and the hyperbola $81x^{2}-144y^{2}=\frac{81 \times 144}{25}$ coincide, then the value of $b$, is
An experiment has $10$ equally likely outcomes. Let $A$ and $B$ be two non-empty events of the experiment. If $A$ consists of $4$ outcomes, the number of outcomes that $B$ must have so that $A$ and $B$ are independent is
Let $\vec{a}=\hat{i}+\hat{j}+\hat{k}, \vec{b}=\hat{i}-\hat{j}+\hat{k}$ and $\vec{c}=\hat{i}-\hat{j}-\hat{k}$ be three vectors. A vector $\vec{v}$ in the plane of $\vec{a}$ and $\vec{b}$ whose projection on $\frac{\vec{c}}{|\vec{c}|}$ is $\frac{1}{\sqrt{3}}$, is
There are 8 students appearing in an examination of which 3 have to appear in Mathematics paper and the remaining 5 in different subjects. Then, the number of ways they can be made to sit in a row, if the candidates in Mathematics cannot sit next to each other is
Let $\vec{a}, \vec{b}$ and $\vec{c}$ be three non-zero vectors, no two of which are collinear, if the vector $\vec{a}+2\vec{b}$ is collinear with $\vec{c}$ and $\vec{b}+3\vec{c}$ is collinear with $\vec{a}$, then $\vec{a}+2\vec{b}+6\vec{c}$ is equal to
A homogeneous system has a non-trivial solution $\iff$ the determinant of its coefficient matrix is $0$.
Coefficient matrix $A=\begin{bmatrix}4 & k & 2\\ k & 4 & 1\\ 2 & 2 & 1\end{bmatrix}$. Hence,
$$
\det(A)=
\begin{vmatrix}
4 & k & 2\\
k & 4 & 1\\
2 & 2 & 1
\end{vmatrix}
=-(k-4)(k-2).
$$
Setting $\det(A)=0 \Rightarrow -(k-4)(k-2)=0 \Rightarrow k=2 \text{ or } k=4.$
Therefore, the number of values of $k$ is $\boxed{2}$.
We count bit strings of length 10 that contain at least one run of five identical bits.
Case 1: Exactly one block of five consecutive 0’s.
The block $00000$ can start at positions 1 to 6, so 6 choices.
The remaining 5 positions can be filled freely with 0 or 1, except they should not create another block of five 0’s.
Valid fillings = $2^5 - 1 = 31$. So number of strings with exactly one block of five 0’s is
$6 \times 31 = 186$
Case 2: Exactly one block of five consecutive 1’s.
By symmetry, the count is the same. $186$
Case 3: One block of five 0’s and one block of five 1’s.
This is possible only when the blocks do not overlap.
The only such strings are
$0000011111$ and $1111100000$
So total such strings = $2$.
Using inclusion–exclusion principle:
$186 + 186 + 2 = 222$
Final Answer: $222$
For any two events $A$ and $B$, the probability that atleast one of them occur is $0.6$. If $A$ and $B$ occur simultaneously with a probability $0.3$ then $P(A')+P(B')$ is
If A, B and C is three angles of a ΔABC, whose area is Δ. Let a, b and c be the sides opposite to the
angles A, B and C respectively. Is $s=\frac{a+b+c}{2}=6$, then the product $\frac{1}{3} s^{2} (s-a)(s-b)(s-c)$ is equal to
Two finite sets $A$ and $B$ are having $m$ and $n$ elements. The total number of subsets of the first set is $56$ more than the total number of subsets of the second set. The value of $m$ and $n$ are
The probability that $A$ speaks truth is $4/5$ while this probability for $B$ is $3/4$. The probability that they contradict each other when asked to speak on a fact is
An arithmetic progression has 3 as its first term.
Also, the sum of the first 8 terms is twice the sum of
the first 5 terms. Then what is the common
difference?
The sum of the expression $\dfrac{1}{\sqrt{1}+\sqrt{2}}+\dfrac{1}{\sqrt{2}+\sqrt{3}}+\dfrac{1}{\sqrt{3}+\sqrt{4}}+\cdots+\dfrac{1}{\sqrt{80}+\sqrt{81}}$ is
Consider the function $f$ defined by
$f(x)=\begin{cases} x^2-1, & x<3 \ 2ax, & x\geq 3 \end{cases}$
for all real number $x$. If $f$ is continuous at $x=3$, then value of $a$ is
A box contains 3 coins, one coin is fair, one coin is two headed and one coin is weighted, so that the
probability of heads appearing is $\frac{1}{3}$ . A coin is selected at random and tossed, then the probability that head appears is
Three house are available in a locality. Three persons apply for the houses. Each applies for one house without consulting other. The probability that all the three apply for the same house is
Out of $2n + 1$ tickets, which are consecutively numbered, three are drawn at random. Then the
probability that the numbers on them are in arithmetic progression is
If a vector $\vec{a}$ makes an equal angle with the coordinate axes and has magnitude 3, then the angle between $\vec{a}$ and each of the three coordinate axes is
If $f(x)=\left\{\begin{matrix} \frac{sin[x]}{[x]} &, [x]\ne0 \\ 0 &, [x]=0 \end{matrix}\right.$ , where [x] is the largest integer but not larger than x, then $\lim_{x\to0}f(x)$ is
The matrix $A$ has $x$ rows and $(x+5)$ columns and the matrix $B$ has $y$ rows and $(11-y)$ columns. If both the matrices $AB$ and $BA$ exist, then value of $x$ and $y$ are
A circus artist is climbing a $20$ m long rope, which is tightly streached and tied from the top of a vertical pole to the ground. Find the height of the pole, if the angle made by the rope with the ground level is $30^\circ$
A student takes a quiz consisting of 5 multiple choice questions. Each question has 4 possible answers. If a student is guessing the answer at random and answer to different are independent, then the probability of atleast one correct answer is
A computer producing factory has only two plants $T_1$ and $T_2$. Plant $T_1$ produces 20% and plant $T_2$ produces 80% of total computers produced. 7% of computers produced in the factory turn out to be defective. It is known that P (computer turns out to be defective given that it is produced in plant $T_1$) = 10P (computer turns out to be defective given that it is produced in plant $T_2$). where P(E) denotes the probability of an event E. A computer produced in the factory is randomly selected and it does not turn out to be defective. Then the probability that it is produced in plant $T_2$ is
There are n equally spaced points 1,2,...,n marked on the circumference of a circle. If the point 15 is directly opposite to the point 49, then the total number of points is
Given: $n$ equally spaced points $1, 2, \ldots, n$ marked on circumference of a circle
Point $15$ is directly opposite to point $49$
Since the points are equally spaced on a circle, two points are directly opposite if they are diametrically opposite
$\therefore$ The number of points between $15$ and $49$ on each semicircle must be equal
Points between $15$ and $49$ (going from $15$ to $49$):
$16, 17, 18, \ldots, 48$
Number of points $= 48 - 16 + 1 = 33$
Since both semicircles must have equal number of points between the opposite points:
Points on other semicircle (from $49$ to $15$) must also be $33$
$\therefore$ Total number of points $= 2 + 33 + 33 = 68$
The mean of 5 observation is 5 and their variance is 12.4. If three of the observations are 1, 2 and 6; then the mean deviation from the mean of the data is:
Let \(u=a-5,\ v=b-5\). Then \(u+v=(a+b)-10=6\) and \(u^2+v^2=36\).
\((u+v)^2 = u^2+v^2+2uv \Rightarrow 36 = 36 + 2uv \Rightarrow uv=0\).
So one of \(u,v\) is 0 ⇒ one of \(a,b\) is 5, the other is \(16-5=11\).
Mean deviation about mean:
\(\displaystyle \text{MD}=\frac{1}{5}\big(|1-5|+|2-5|+|6-5|+|5-5|+|11-5|\big)
\) \( =\frac{1}{5}(4+3+1+0+6)=\frac{14}{5}=2.8.\)
Given: $S = \{1, 2, \ldots, n\}$
We need to find number of pairs $(A, B)$ such that $A \subseteq B \subseteq S$
Method: Element-wise analysis
For each element $i \in S$, there are three possibilities:
$i \notin A$ and $i \notin B$
$i \notin A$ and $i \in B$
$i \in A$ and $i \in B$
Note: The case $i \in A$ and $i \notin B$ is not possible since $A \subseteq B$
So each element independently has exactly $3$ choices
Since there are $n$ elements in $S$:
Total number of pairs $= \underbrace{3 \times 3 \times \cdots \times 3}_{n \text{ times}}$
$\therefore \boxed{3^n}$
A matrix $M_r$ is defined as $M_r=\begin{bmatrix} r &r-1 \\ r-1&r \end{bmatrix} , r \in N$ then the value of $det(M_1) + det(M_2) +...+ det(M_{2015})$ is
In an examination of nine papers, a candidate has to pass in more papers than the number of papers in which he fails in order to be successful. The number of ways in which he can be unsuccessful is
The value of $sin^{-1}\frac{1}{\sqrt{2}}+sin^{-1}\frac{\sqrt{2}-\sqrt{1}}{\sqrt{6}}+sin^{-1}\frac{\sqrt{3}-\sqrt{2}}{\sqrt{12}}+...$ to infinity , is equal to
For a group of 100 candidates, the mean and standard deviation of scores were found to be 40 and 15
respectively. Later on, it was found that the scores 25 and 35 were misread as 52 and 53 respectively. Then the
corrected mean and standard deviation corresponding to the corrected figures are
Two forces F1 and F2 are used to pull a car, which met an accident. The angle between the two forces is θ . Find the values of θ for which the resultant force
is equal to
If PQ is a double ordinate of the hyperbola $\frac{x^{2}}{a^{2}}-\frac{y^{2}}{b^{2}}=1$ such that OPQ is an equilateral triangle,
where O is the centre of the hyperbola, then which of the following is true?
Let $f(x) = x^2 - bx + c$, b is an odd positive integer. If f(x)=0 has two prime numbers as roots and b + c = 35, then the global minimum value of f(x) is
The sum of infinite terms of decreasing GP is equal to the greatest value of the function $f(x) = x^3
+ 3x – 9$ in the
interval [–2, 3] and difference between the first two terms is f '(0). Then the common ratio of the GP is
Forces of magnitude 5, 3, 1 units act in the directions
6i + 2j + 3k, 3i - 2j + 6k, 2i - 3j - 6k respectively on a particle which is displaced from the
point (2, −1, −3) to (5, −1, 1). The total work done by the force is
In a right angled triangle, the hypotenuse is four times the perpendicular drawn to it from the opposite vertex. The value of one of the acute angles is
Let $f(x) = x^2 - x\sin x - \cos x$
Differentiating with respect to $x$:
$f'(x) = 2x - \sin x - x\cos x + \sin x$
$f'(x) = 2x - x\cos x$
$f'(x) = x(2 - \cos x)$
Since $-1 \leq \cos x \leq 1$ $\Rightarrow$ $2 - \cos x \geq 1 > 0$ always
$\therefore$ Sign of $f'(x)$ depends on sign of $x$
$f'(x) < 0$ for $x < 0$ and $f'(x) > 0$ for $x > 0$
$\therefore f(x)$ has minimum at $x = 0$
Minimum value $= f(0) = 0 - 0 - \cos 0 = -1 < 0$
Also, $f(-x) = (-x)^2 - (-x)\sin(-x) - \cos(-x)$
$= x^2 - x\sin x - \cos x = f(x)$
$\therefore f(x)$ is an even function
As $x \rightarrow \pm\infty$, $f(x) \rightarrow +\infty$
Since $f(0) = -1 < 0$ is minimum and $f(x) \rightarrow +\infty$ on both sides
$\therefore$ Graph of $f(x)$ crosses $x$-axis at exactly two points
One in $(-\infty, 0)$ and one in $(0, \infty)$
$\therefore$ Total number of points $= \boxed{2}$
A is targeting B, B and C are targeting A. Probability of hitting the target by A, B and C are $\frac{2}{3}, \frac{1}{2}$ and $\frac{1}{3}$ respectively. If A is hit then the probability that B hits the target and C does not, is
The average marks of boys in a class is 52 and that of girls is 42. The average marks of boys and girls
combined is 50. The percentage of boys in the class is
Given averages: Boys = 52, Girls = 42, Combined = 50.
Let the proportion of boys be \(p\) (so girls = \(1-p\)).
Weighted mean gives:
$$52p + 42(1-p) = 50$$
$$52p + 42 - 42p = 50 \Rightarrow 10p = 8 \Rightarrow p = 0.8.$$
Percentage of boys \(= 0.8 \times 100\% = \boxed{80\%}\).
There are $4$ books on fairy tales, $5$ novels and $3$ plays. In how many ways can they be arranged in the order books on fairy tales, novels and then plays so that books of same category are put together
Given:
$4$ books on fairy tales, $5$ novels, $3$ plays
The order of arrangement is fixed as:
Fairy Tales $\rightarrow$ Novels $\rightarrow$ Plays
Step 1: Arrange books within each category
Fairy tales books can be arranged among themselves $= 4!= 24$ ways
Novels can be arranged among themselves $= 5! = 120$ ways
Plays can be arranged among themselves $= 3! = 6$ ways
Step 2: Total number of arrangements
$= 4! \times 5! \times 3!$
$= 24 \times 120 \times 6$
$\therefore \boxed{= 17280 \text{ ways}}$
If a, b, c are three non-zero vectors with no two of
which are collinear, a + 2b is collinear with c and b + 3c is collinear with a , then | a + 2b + 6c | will
be equal to
Suppose a population $A$ has $100$ observations $101,102,\ldots,200$ and another population $B$ has $100$ observations $151,152,\ldots,250$. If $V_A$ and $V_B$ represent variance of the two populations respectively, then $\dfrac{V_A}{V_B}$ is
Population $A$: $101, 102, \ldots, 200$
Population $B$: $151, 152, \ldots, 250$
Using Property:
Variance is independent of change of origin
i.e., if each observation is increased or decreased by a constant, variance remains unchanged
Here, each observation of $B$ = each observation of $A$ $+ 50$
$\Rightarrow$ Population $B$ is obtained by adding $50$ to each observation of population $A$
$\Rightarrow V_B = V_A$
$\therefore \dfrac{V_A}{V_B} = \boxed{1}$
If $\prod ^n_{i=1}\tan ({{\alpha}}_i)=1\, \forall{{\alpha}}_i\, \in\Bigg{[}0,\, \frac{\pi}{2}\Bigg{]}$ where i=1,2,3,...,n. Then maximum value of $\prod ^n_{i=1}\sin ({{\alpha}}_i)$.
If $\vec{a}, \vec{b}$ are vector such that $|\vec{a}+\vec{b}|=\sqrt{29}$ and
$\vec{a}\times (2\hat{i}+3\hat{j}+4\hat{k}) = (2\hat{i}+3\hat{j}+4\hat{k})\times \vec{b}$, then a possible value of $(\vec{a}+\vec{b})\cdot(-7\hat{i}+2\hat{j}+3\hat{k})$ is
A speaks truth in 60% and B speaks the truth in 50% cases. In what percentage of cases they are likely incontradict each other while narrating some incident is
A harbour lies in a direction 60° South of West from a fort and at a distance 30 km from it, a ship sets out from the harbour at noon and sails due East at 10 km an hour. The time at which the ship will be 70 km from the fort is
If $\overrightarrow{{a}}$ and $\overrightarrow{{b}}$ are vectors in space, given by $\overrightarrow{{a}}=\frac{\hat{i}-2\hat{j}}{\sqrt[]{5}}$ and $\overrightarrow{{b}}=\frac{2\hat{i}+\hat{j}+3\hat{k}}{\sqrt[]{14}}$, then the value of$(2\vec{a} + \vec{b}).[(\vec{a} × \vec{b}) × (\vec{a} – 2\vec{b})]$ is
Given ellipse: $\dfrac{x^2}{a^2} + \dfrac{y^2}{b^2} = 1$
**Setting up the Rectangle:**
Let $P(a\cos\theta,\ b\sin\theta)$ be a point on the ellipse
Then the rectangle has:
Length $= 2a\cos\theta$
Breadth $= 2b\sin\theta$
**Area of Rectangle:**
$A = 2a\cos\theta \times 2b\sin\theta$
$A = 4ab\sin\theta\cos\theta$
$A = 2ab\sin 2\theta$
**Maximizing the Area:**
$A$ is maximum when $\sin 2\theta$ is maximum
$\Rightarrow \sin 2\theta = 1$
$\Rightarrow 2\theta = 90^\circ$
$\Rightarrow \theta = 45^\circ$
**Maximum Area:**
$A_{max} = 2ab \times 1$
$\therefore \boxed{A_{max} = 2ab}$
Let $\vec{A} = 2\hat{i} + \hat{j} – 2\hat{k}$ and $\vec{B} = \hat{i} + \hat{j}$, If $\vec{C}$ is a vector such that $|\vec{C} – \vec{A}| = 3$ and the angle between A × B and C is ${30^{\circ}}$, then $|(\vec{A} × \vec{B}) × \vec{C}|$ = 3 then the value of $\vec{A}.\vec{C}$ is equal to
A professor has 24 text books on computer science and is concerned about their coverage of the topics (P) compilers, (Q) data structures and (R) Operating systems. The following data gives the number of books that contain material on these topics: $n(P) = 8, n(Q) = 13, n(R) = 13,
n(P \cap R) = 3, n(P \cap R) = 3, n(Q \cap R) = 3, n(Q \cap R) = 6, n(P \cap Q \cap R) = 2 $ where $n(x)$ is the cardinality of the set $x$. Then the number of text books that have no material on compilers is
If $a_1,a_2,\ldots,a_n$ are in A.P. and $a_1=0$ then the value of
$\left(\dfrac{a_3}{a_2}+\dfrac{a_4}{a_3}+\cdots+\dfrac{a_n}{a_{n-1}}\right)-a_2\left(\dfrac{1}{a_2}+\dfrac{1}{a_3}+\cdots+\dfrac{1}{a_{n-2}}\right)$
is equal to
If $\vec{a}$ and $\vec{b}$ are vectors such that $|\vec{a}|=13$, $|\vec{b}|=5$ and $\vec{a} . \vec{b} =60$then the value of $|\vec{a} \times \vec{b}|$ is
Two ships are sailing in the sea on the two sides of a lighthouse. The angle of elevation of
the top of the lighthouse is observed from the ships are 30° degree and 45° repectively.
If the lighthouse is 100 m high, the distance between the two ships is
The permutations of ${a,b,c,d,e,f,g}$ are listed in lexicographic order. Which of the following permutations are just before and just after the permutation $bacdefg$ ?
Two towers face each other separated by a distance of 25 meters. As seen from the top of the first tower, the angle of depression of the second tower’s base is 60° and that of the top is 30°. The height (in meters) of the second tower is
Let the first tower be \(AB\) (top \(A\), base \(B\)) and the second tower be \(CD\) (top \(C\), base \(D\)). The bases \(B\) and \(D\) are 25 m apart.
From the top \(A\): angle of depression to base \(D\) is \(60^\circ\) and to top \(C\) is \(30^\circ\).
From right \(\triangle ABD\):
\[
\tan 60^\circ=\frac{AB}{BD}=\frac{AB}{25}\;\Rightarrow\; AB=25\sqrt{3}.
\]
From right \(\triangle ACD\): vertical difference \(=AB-CD\) and horizontal \(=25\).
\[
\tan 30^\circ=\frac{AB-CD}{25}=\frac{1}{\sqrt{3}}
\;\Rightarrow\; AB-CD=\frac{25}{\sqrt{3}}.
\]
The foci of the ellipse $\dfrac{x^2}{16} + \dfrac{y^2}{b^2} = 1$ and the hyperbola $\dfrac{x^2}{144} - \dfrac{y^2}{81} = \dfrac{1}{25}$ coincide. Then the value of $b^2$ is