Qus : 20
NIMCET PYQ
3
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
1
$n+1$ 2
$n-1$ 3
$2n$ 4
$2n+3$ Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2008 PYQ
Solution 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.
Step 2: Find common difference $d$
$d = \dfrac{\dfrac{1}{b}-\dfrac{1}{a}}{n+1} = \dfrac{a-b}{ab(n+1)}$
Step 3: Find $H_1$ and $H_n$
$\dfrac{1}{H_1} = \dfrac{1}{a} + d = \dfrac{a+bn}{ab(n+1)}$
$\Rightarrow H_1 = \dfrac{ab(n+1)}{a+bn}$
$\dfrac{1}{H_n} = \dfrac{1}{b} - d = \dfrac{an+b}{ab(n+1)}$
$\Rightarrow H_n = \dfrac{ab(n+1)}{an+b}$
Step 4: Evaluate $\dfrac{H_1+a}{H_1-a}$ using Componendo-Dividendo
$\dfrac{H_1}{a} = \dfrac{b(n+1)}{a+bn}$
Applying componendo-dividendo:
$\dfrac{H_1+a}{H_1-a} = \dfrac{b(n+1)+(a+bn)}{b(n+1)-(a+bn)} $
$= \dfrac{a+b(2n+1)}{b-a} \quad \cdots(1)$
Step 5: Evaluate $\dfrac{H_n+b}{H_n-b}$ using Componendo-Dividendo
$\dfrac{H_n}{b} = \dfrac{a(n+1)}{an+b}$
Applying componendo-dividendo:
$\dfrac{H_n+b}{H_n-b} = \dfrac{a(n+1)+(an+b)}{a(n+1)-(an+b)} $
$= \dfrac{b+a(2n+1)}{a-b} \quad \cdots(2)$
Step 6: Add (1) and (2)
$\dfrac{H_1+a}{H_1-a}+\dfrac{H_n+b}{H_n-b} $
$= \dfrac{a+b(2n+1)}{b-a} + \dfrac{b+a(2n+1)}{a-b}$
$= \dfrac{a+b(2n+1) - b - a(2n+1)}{b-a}$
$= \dfrac{(a-b) + (2n+1)(b-a)}{b-a}$
$= \dfrac{(b-a)(2n+1)-(b-a)}{b-a}$
$= (2n+1) - 1$
$= 2n$
Answer: $\dfrac{H_1+a}{H_1-a}+\dfrac{H_n+b}{H_n-b} = \boxed{2n}$
Qus : 25
NIMCET PYQ
1
The number of all even integers between 99 and 999 which are not multiple of 3 and 5 is
1
240 2
250 3
245 4
235 Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2025 PYQ
Solution
Solution:
Even numbers from 100 to 998: count $= \frac{998-100}{2}+1=450$.
Exclude evens divisible by $3$ or $5$ using inclusion–exclusion:
Multiples of $6$ in $[100,998]$: $\lfloor 998/6 \rfloor-\lfloor 99/6 \rfloor = 166-16=150$.
Multiples of $10$ in $[100,998]$: $\lfloor 998/10 \rfloor-\lfloor 99/10 \rfloor = 99-9=90$.
Multiples of $30$ in $[100,998]$: $\lfloor 998/30 \rfloor-\lfloor 99/30 \rfloor = 33-3=30$.
Forbidden $=150+90-30=210$ ⇒ Allowed $=450-210={240}$.
Qus : 26
NIMCET PYQ
2
The roots of the quadratic equation $3x^2-px+q=0$ are the $10^{\text{th}}$ and $11^{\text{th}}$ terms of an arithmetic progression with common difference $\frac{3}{2}$. If the sum of the first $11$ terms of this arithmetic progression is $88$, then $q-2p$ is:
1
464 2
474 3
484 4
494 Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2026 PYQ
Solution Let the first term of the arithmetic progression be $a$.
Common difference is:
$d=\frac{3}{2}$
Sum of first $11$ terms is:
$S_{11}=88$
Formula for sum of first $n$ terms:
$S_n=\frac{n}{2}[2a+(n-1)d] $
So,
$88=\frac{11}{2}[2a+10d] $
Substitute $d=\frac{3}{2}$:
$88=\frac{11}{2}\left[2a+10\times \frac{3}{2}\right] $
$88=\frac{11}{2}[2a+15] $
Now,
$2a+15=16$
$2a=1$
$a=\frac{1}{2}$
The $10^{\text{th}}$ term is:
$T_{10}=a+9d$
$T_{10}=\frac{1}{2}+9\times \frac{3}{2}$
$T_{10}=\frac{1}{2}+\frac{27}{2}$
$T_{10}=14$
The $11^{\text{th}}$ term is:
$T_{11}=a+10d$
$T_{11}=\frac{1}{2}+10\times \frac{3}{2}$
$T_{11}=\frac{1}{2}+15$
$T_{11}=\frac{31}{2}$
So, the roots of $3x^2-px+q=0$ are $14$ and $\frac{31}{2}$.
For equation $3x^2-px+q=0$,
Sum of roots:
$\frac{p}{3}=14+\frac{31}{2}$
$\frac{p}{3}=\frac{28+31}{2}$
$\frac{p}{3}=\frac{59}{2}$
$p=\frac{177}{2}$
Product of roots:
$\frac{q}{3}=14\times \frac{31}{2}$
$\frac{q}{3}=217$
$q=651$
Now,
$q-2p=651-2\times \frac{177}{2}$
$q-2p=651-177$
$q-2p=474$
Therefore, the correct answer is option $2$.Given,
Qus : 27
NIMCET PYQ
1
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?
1
25 2
13 3
1 4
7 Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2017 PYQ
Solution Let the three terms in A.P. be a – d, a, a + d.
given that a – d + a + a + d = 21
a = 7
then the three term in A.P. are 7 – d, 7, 7 + d
According to given condition 9 – d, 9, 21 + d are in G.P.
(9)2 = (9 – d) (21 + d)
81 = 189 + 9d – 21d – d2
81 = 189 – 12d – d2
d2 + 12d – 108 = 0
d(d + 18) – 6 (d + 18) = 0
(d – 6) (d + 18) = 0
We get, d = 6, –18
Putting d = 6 in the term 7 – d, 7, 7 + d we get 1, 7, 13.
Qus : 28
NIMCET PYQ
2
Which of the following is a value of $n$ if$\left(\sum_{k=1}^{n}(-1)^{k-1}k\right)^2-\sum_{k=1}^{n}(-1)^{k-1}k^2+2450=0$?
1
98 2
99 3
100 4
101 Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2026 PYQ
Solution Given equation is
$\left(\sum_{k=1}^{n}(-1)^{k-1}k\right)^2-\sum_{k=1}^{n}(-1)^{k-1}k^2+2450=0$
Check for odd $n$.
Let
$n=2m-1$
Then,
$\sum_{k=1}^{n}(-1)^{k-1}k=1-2+3-4+\cdots+(2m-1)$
Pairing terms,
$(1-2)+(3-4)+\cdots+[(2m-3)-(2m-2)] +(2m-1)$
$=-(m-1)+(2m-1)$
$=m$
So,
$\left(\sum_{k=1}^{n}(-1)^{k-1}k\right)^2=m^2$
Now,
$\sum_{k=1}^{n}(-1)^{k-1}k^2=1^2-2^2+3^2-4^2+\cdots+(2m-1)^2$
For odd $n=2m-1$,
$\sum_{k=1}^{n}(-1)^{k-1}k^2=m(2m-1)$
Now put in the equation:
$m^2-m(2m-1)+2450=0$
$m^2-2m^2+m+2450=0$
$-m^2+m+2450=0$
$m^2-m-2450=0$
Now factorize:
$m^2-m-2450=0$
$m^2-50m+49m-2450=0$
$m(m-50)+49(m-50)=0$
$(m-50)(m+49)=0$
Since $m$ is positive,
$m=50$
Therefore,
$n=2m-1$
$n=2(50)-1$
$n=99$
Qus : 29
NIMCET PYQ
1
If $H_1,H_2,\ldots,H_n$ are n harmonic means between a and b $(b\ne a)$;,then $\frac{{{H}}_n+a}{{{H}}_n-a}+\frac{{{H}}_n+b}{{{H}}_n-b}$
1
$2n$ 2
$n+1$ 3
$n-1$ 4
$2n+1$ Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2021 PYQ
Solution 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.
Step 2: Find common difference $d$
$d = \dfrac{\dfrac{1}{b}-\dfrac{1}{a}}{n+1} = \dfrac{a-b}{ab(n+1)}$
Step 3: Find $H_1$ and $H_n$
$\dfrac{1}{H_1} = \dfrac{1}{a} + d = \dfrac{a+bn}{ab(n+1)}$
$\Rightarrow H_1 = \dfrac{ab(n+1)}{a+bn}$
$\dfrac{1}{H_n} = \dfrac{1}{b} - d = \dfrac{an+b}{ab(n+1)}$
$\Rightarrow H_n = \dfrac{ab(n+1)}{an+b}$
Step 4: Evaluate $\dfrac{H_1+a}{H_1-a}$ using Componendo-Dividendo
$\dfrac{H_1}{a} = \dfrac{b(n+1)}{a+bn}$
Applying componendo-dividendo:
$\dfrac{H_1+a}{H_1-a} = \dfrac{b(n+1)+(a+bn)}{b(n+1)-(a+bn)} $
$= \dfrac{a+b(2n+1)}{b-a} \quad \cdots(1)$
Step 5: Evaluate $\dfrac{H_n+b}{H_n-b}$ using Componendo-Dividendo
$\dfrac{H_n}{b} = \dfrac{a(n+1)}{an+b}$
Applying componendo-dividendo:
$\dfrac{H_n+b}{H_n-b} = \dfrac{a(n+1)+(an+b)}{a(n+1)-(an+b)} $
$= \dfrac{b+a(2n+1)}{a-b} \quad \cdots(2)$
Step 6: Add (1) and (2)
$\dfrac{H_1+a}{H_1-a}+\dfrac{H_n+b}{H_n-b} $
$= \dfrac{a+b(2n+1)}{b-a} + \dfrac{b+a(2n+1)}{a-b}$
$= \dfrac{a+b(2n+1) - b - a(2n+1)}{b-a}$
$= \dfrac{(a-b) + (2n+1)(b-a)}{b-a}$
$= \dfrac{(b-a)(2n+1)-(b-a)}{b-a}$
$= (2n+1) - 1$
$= 2n$
Answer: $\dfrac{H_1+a}{H_1-a}+\dfrac{H_n+b}{H_n-b} = \boxed{2n}$
Qus : 30
NIMCET PYQ
1
If $a_1, a_2,...a_n$ are positive real numbers whose product is a fixed number c, then the minimum of $a_1, a_2, ....2a_n$ is
1
$n(2c)^{1/n}$ 2
$(n+1)c^{1/n}$ 3
$\frac{(2n)!}{(n!)^2}$ 4
$(n+1)(2c)^{1/n}$ Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2018 PYQ
Solution Key Concept: AM-GM Inequality
$\dfrac{a_1 + a_2 + \cdots + a_n}{n} \geq (a_1 \cdot a_2 \cdots a_n)^{1/n}$
Step 1: Rewrite the sum
$a_1 + a_2 + \cdots + a_{n-1} + 2a_n$
This has $n$ terms: $(a_1, a_2, \ldots, a_{n-1}, 2a_n)$
Step 2: Apply AM-GM
$\dfrac{a_1 + a_2 + \cdots + a_{n-1} + 2a_n}{n} \geq (a_1 \cdot a_2 \cdots a_{n-1} \cdot 2a_n)^{1/n}$
$\geq (2 \cdot a_1 a_2 \cdots a_n)^{1/n}$
$\geq (2c)^{1/n}$
Step 3: Find minimum
$a_1 + a_2 + \cdots + 2a_n \geq n(2c)^{1/n}$
Minimum value $= n(2c)^{1/n}$
Equality holds when $a_1 = a_2 = \cdots = a_{n-1} = 2a_n$
Answer: Minimum value $= \boxed{n(2c)^{1/n}}$
Qus : 31
NIMCET PYQ
2
The four geometric means between 2 and 64 are
1
$\frac{1}{4},\frac{1}{8},\frac{1}{16},\frac{1}{32}$ 2
$4,8,16,32$ 3
$4\sqrt[]{2},8,16\sqrt[]{2},32$ 4
None of the above Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2021 PYQ
Solution Step 1: Set up the GP
The sequence is: $2,\ G_1,\ G_2,\ G_3,\ G_4,\ 64$
Total terms $= 6$, so $n = 6$
Step 2: Find common ratio $r$
$a = 2,\ a_6 = 64$
$a_6 = a \cdot r^{n-1}$
$64 = 2 \cdot r^5$
$r^5 = 32$
$r^5 = 2^5$
$r = 2$
Step 3: Find the four geometric means
$G_1 = ar = 2 \times 2 = 4$
$G_2 = ar^2 = 2 \times 4 = 8$
$G_3 = ar^3 = 2 \times 8 = 16$
$G_4 = ar^4 = 2 \times 16 = 32$
Answer: The four geometric means are $\boxed{4, 8, 16, 32}$
Qus : 32
NIMCET PYQ
3
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
1
1 2
2 3
3 4
5 Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2025 PYQ
Solution Let first term $= a$, common difference $= d$, so $t_n = a + (n-1)d$
Step 1: Expand $\displaystyle\sum_{l=0}^{18} t_{3l+1} = 1197$
Terms: $t_1, t_4, t_7, \ldots, t_{55}$ (19 terms, $l = 0$ to $18$)
$t_{3l+1} = a + 3ld$
$\displaystyle\sum_{l=0}^{18}(a + 3ld) $
$= 19a + 3d\cdot\dfrac{18 \times 19}{2} $
$= 19a + 513d = 1197$
$\Rightarrow a + 27d = 63 \quad \cdots(1)$
Step 2: Use $t_7 + 3t_{22} = 174$
$t_7 = a + 6d,\quad t_{22} = a + 21d$
$(a + 6d) + 3(a + 21d) = 174$
$4a + 69d = 174 \quad \cdots(2)$
Step 3: Solve (1) and (2)
From (1): $a = 63 - 27d$
Substitute in (2):
$4(63 - 27d) + 69d = 174$
$252 - 108d + 69d = 174$
$-39d = -78$
$d = 2$
$a = 63 - 54 = 9$
Step 4: Find $\displaystyle\sum_{l=1}^{9} t_l^2$
$t_l = 9 + (l-1) \times 2 = 7 + 2l$
$\displaystyle\sum_{l=1}^{9} t_l^2 = \sum_{l=1}^{9}(7+2l)^2 = \sum_{l=1}^{9}(49 + 28l + 4l^2)$
$= 49(9) + 28\cdot\dfrac{9 \times 10}{2} + 4\cdot\dfrac{9 \times 10 \times 19}{6}$
$= 441 + 1260 + 1140$
$= 2841$
Step 5: Find $b$
$947b = 2841$
$b = \dfrac{2841}{947} = 3$
Answer: $b = \boxed{3}$
Qus : 33
NIMCET PYQ
1
If a, b, c are in geometric progression, then $log_{ax}^{a}, log_{bx}^{a}$ and $log_{cx}^{a}$ are in
1
Arithmetic progression 2
Geometric progression 3
Harmonic progression 4
Arithmetico-geometric progression Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2015 PYQ
Solution $ a, b, c $ are in G.P.
$ \Rightarrow b^2 = ac $
Take logs base $a$:
$ \log_a a = 1,\quad \log_a b,\quad \log_a c $
Since $ a, b, c $ are in G.P.
$ \Rightarrow \log_a a,\ \log_a b,\ \log_a c $ are in A.P.
Now given:
$ \log_a(ax) = \log_a a + \log_a x = 1 + \log_a x $
$ \log_a(bx) = \log_a b + \log_a x $
$ \log_a(cx) = \log_a c + \log_a x $
These are:
$ (1 + k),\ (\log_a b + k),\ (\log_a c + k) $ where $k = \log_a x$
Adding same constant does not change A.P. nature
$\boxed{\text{They are in A.P.}}$
Qus : 34
NIMCET PYQ
2
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
1
$\frac{9}{10}$ 2
$\frac{4}{5}$ 3
$\frac{14}{15}$ 4
$\frac{7}{15}$ Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2015 PYQ
Solution Step 1: General term
$T_n = \dfrac{1}{(n+1)\sqrt{n}+n\sqrt{n+1}}$
Step 2: Rationalize by multiplying numerator and denominator by $(n+1)\sqrt{n}-n\sqrt{n+1}$
Denominator becomes:
$[(n+1)\sqrt{n}]^2 - [n\sqrt{n+1}]^2$
$ = n(n+1)^2 - n^2(n+1) $
$= n(n+1)(n+1-n)$
$ = n(n+1)$
So:
$T_n = \dfrac{(n+1)\sqrt{n} - n\sqrt{n+1}}{n(n+1)}$
$= \dfrac{\sqrt{n}}{n} - \dfrac{\sqrt{n+1}}{n+1}$
$= \dfrac{1}{\sqrt{n}} - \dfrac{1}{\sqrt{n+1}}$
Step 3: Telescoping sum from $n=1$ to $n=24$
$\displaystyle\sum_{n=1}^{24} T_n = \left(\dfrac{1}{\sqrt{1}} - \dfrac{1}{\sqrt{2}}\right) + \left(\dfrac{1}{\sqrt{2}} - \dfrac{1}{\sqrt{3}}\right) + \cdots + \left(\dfrac{1}{\sqrt{24}} - \dfrac{1}{\sqrt{25}}\right)$
$= \dfrac{1}{\sqrt{1}} - \dfrac{1}{\sqrt{25}}$
$= 1 - \dfrac{1}{5}$
$= \dfrac{4}{5}$
Answer: $\boxed{\dfrac{4}{5}}$
Qus : 35
NIMCET PYQ
1
Consider the sequence:
$72,69,66,\ldots$
The numbers continue in the same pattern as long as they remain positive. What will be the maximum possible sum of the terms of this sequence?
1
900 2
897 3
882 4
903 Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2026 PYQ
Solution The sequence is:
$72,69,66,\ldots$
This is an arithmetic progression with first term:
$a=72$
Common difference:
$d=-3$
The terms continue as long as they remain positive.
Last positive term will be $3$.
Now,
$a_n=3$
Using formula:
$a_n=a+(n-1)d$
$3=72+(n-1)(-3)$
$3=72-3n+3$
$3=75-3n$
$3n=72$
$n=24$
Now, sum of first $24$ terms is:
$S_n=\frac{n}{2}(a+l)$
$S_{24}=\frac{24}{2}(72+3)$
$S_{24}=12\times 75$
$S_{24}=900$
Qus : 36
NIMCET PYQ
1
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?
1
3/4 2
1/2 3
1/4 4
4/3 Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2020 PYQ
Solution
Step 1: Write sum formula
$S_n = \dfrac{n}{2}[2a + (n-1)d]$
$S_8 = \dfrac{8}{2}[6 + 7d] $
$= 4(6+7d) $
$= 24 + 28d$
$S_5 = \dfrac{5}{2}[6 + 4d] $
$= \dfrac{5}{2}(6+4d) $
$= 15 + 10d$
Step 2: Apply condition $S_8 = 2S_5$
$24 + 28d = 2(15 + 10d)$
$24 + 28d = 30 + 20d$
$8d = 6$
$d = \dfrac{3}{4}$
Answer: $d = \boxed{\dfrac{3}{4}}$
Qus : 37
NIMCET PYQ
4
A group of 630 children is arranged in rows for a group photograph session.
Each row contains three fewer children than the row in front of it.
What number of rows is not possible?
1
3 2
4 3
5 4
6 Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2008 PYQ
Solution Step 1: Set up AP
Let first row (front) have $a$ children, common difference $d = -3$
For $n$ rows, sum $= 630$:
$S_n = \dfrac{n}{2}[2a + (n-1)(-3)] = 630$
$n[2a - 3(n-1)] = 1260$
$2a = \dfrac{1260}{n} + 3(n-1)$
$a = \dfrac{630}{n} + \dfrac{3(n-1)}{2}$
Step 2: Conditions for valid solution
$a$ must be a positive integer , and last row $= a + (n-1)(-3) > 0$
$\Rightarrow a > 3(n-1)$
$\Rightarrow \dfrac{630}{n} + \dfrac{3(n-1)}{2} > 3(n-1)$
$\Rightarrow \dfrac{630}{n} > \dfrac{3(n-1)}{2}$
$\Rightarrow 1260 > 3n(n-1)$
$\Rightarrow n(n-1) < 420$
$\Rightarrow n \leq 21$ (since $21 \times 20 = 420$, not $< 420$, so $n \leq 20$)
Step 3: Also $a$ must be a positive integer
$a = \dfrac{630}{n} + \dfrac{3(n-1)}{2}$ must be a positive integer.
For $a$ to be integer: $\dfrac{630}{n}$ and $\dfrac{3(n-1)}{2}$ must together give integer.
Check $n = 6$: $a = \dfrac{630}{6} + \dfrac{3(5)}{2} = 105 + 7.5 = 112.5$ — not integer! ✗
Check $n = 7$: $a = \dfrac{630}{7} + \dfrac{3(6)}{2} = 90 + 9 = 99$ ✓
Check $n = 9$: $a = \dfrac{630}{9} + \dfrac{3(8)}{2} = 70 + 12 = 82$ ✓
Check $n = 14$: $a = \dfrac{630}{14} + \dfrac{3(13)}{2} = 45 + 19.5 = 64.5$ — not integer! ✗
Qus : 39
NIMCET PYQ
3
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
1
$$\frac{-2}{3}$$ 2
$$\frac{4}{3}$$ 3
$$\frac{+2}{3}$$ 4
$$\frac{-4}{3}$$ Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2023 PYQ
Solution
? GP and Function Relation
Given: \( f(x) = x^3 + 3x - 9 \)
The sum of infinite GP = max value of \( f(x) \) on [−2, 3]
The difference between first two terms = \( f'(0) \)
Step 1: \( f(x) \) is increasing ⇒ Max at \( x = 3 \)
\( f(3) = 27 \Rightarrow \frac{a}{1 - r} = 27 \)
Step 2: \( f'(x) = 3x^2 + 3 \Rightarrow f'(0) = 3 \)
⇒ \( a(1 - r) = 3 \)
Step 3: Solve:
\( a = 27(1 - r) \)
\( \Rightarrow 27(1 - r)^2 = 3 \Rightarrow (1 - r)^2 = \frac{1}{9} \Rightarrow r = \frac{2}{3} \)
✅ Final Answer:
\( r = \frac{2}{3} \)
Qus : 40
NIMCET PYQ
4
The arithmetic mean of two numbers a and b is 5, and the harmonic mean is 3.2. Find the numbers a and b.
1
a=3, b=7 2
a=4, b=6 3
a=1, b=9 4
a=2, b=8 Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2026 PYQ
Solution AM $=5$ $\frac{a+b}{2}=5$ $a+b=10$ HM $=3.2$ $\frac{2ab}{a+b}=3.2$ $\frac{2ab}{10}=3.2$ $ab=16$ Therefore, $a$ and $b$ are roots of $x^2-10x+16=0$ $(x-8)(x-2)=0$ $\boxed{a=8,\quad b=2}$
Qus : 41
NIMCET PYQ
1
Let $A_k$ be the arithmetic mean of squares of $k$ natural numbers. If $\sum_{k=1}^{n}(6A_k-3k)=31$, find the value of $n$.
1
3 2
2 3
4 4
1 Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2026 PYQ
Solution $A_k=\frac{1^2+2^2+3^2+\cdots+k^2}{k}$
$A_k=\frac{\frac{k(k+1)(2k+1)}{6}}{k}$
$A_k=\frac{(k+1)(2k+1)}{6}$
Now,
$6A_k-3k=(k+1)(2k+1)-3k$
$=2k^2+3k+1-3k$
$=2k^2+1$
Given,
$\sum_{k=1}^{n}(6A_k-3k)=31$
$\sum_{k=1}^{n}(2k^2+1)=31$
For $n=3$,
$(2\cdot1^2+1)+(2\cdot2^2+1)+(2\cdot3^2+1)$
$=3+9+19=31$
Therefore,
$n=3$
Qus : 42
NIMCET PYQ
1
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
1
$(n-2)+\dfrac{1}{n-2}$ 2
$\dfrac{1}{n-2}$ 3
$n-2$
4
$n-\dfrac{1}{n-2}$ Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2016 PYQ
Solution
Qus : 43
NIMCET PYQ
2
If a, b, c, d are in HP and arithmetic mean of ab, bc, cd is 9 then which of the following number is the value of ad?
1
3 2
9 3
12 4
4 Go to Discussion
NIMCET Previous Year PYQ
NIMCET NIMCET 2023 PYQ
Solution $a, b, c, d$ are in H.P.
$\Rightarrow \frac{1}{a}, \frac{1}{b}, \frac{1}{c}, \frac{1}{d}$ are in A.P.
$\Rightarrow \frac{2}{b} = \frac{1}{a} + \frac{1}{c}$ and $\frac{2}{c} = \frac{1}{b} + \frac{1}{d}$
Given A.M. of $ab, bc, cd$ is $9$:
$\frac{ab + bc + cd}{3} = 9$
$\Rightarrow ab + bc + cd = 27$
Now multiply:
$\frac{2}{b} = \frac{1}{a} + \frac{1}{c} $
$\Rightarrow 2ac = b(a + c)$
$\frac{2}{c} = \frac{1}{b} + \frac{1}{d} \Rightarrow 2bd = c(b + d)$
Multiply both:
$4abcd = bc(a + c)(b + d)$
Cancel $bc$:
$4ad = (a + c)(b + d)$
Expand RHS:
$4ad = ab + ad + bc + cd$
$\Rightarrow 3ad = ab + bc + cd$
But $ab + bc + cd = 27$:
$\Rightarrow 3ad = 27$
$\Rightarrow ad = 9$
$\boxed{9}$
[{"qus_id":"3776","year":"2018"},{"qus_id":"3752","year":"2018"},{"qus_id":"3751","year":"2018"},{"qus_id":"3900","year":"2019"},{"qus_id":"3931","year":"2019"},{"qus_id":"3932","year":"2019"},{"qus_id":"3939","year":"2019"},{"qus_id":"4267","year":"2017"},{"qus_id":"4278","year":"2017"},{"qus_id":"9447","year":"2020"},{"qus_id":"10684","year":"2021"},{"qus_id":"10689","year":"2021"},{"qus_id":"11125","year":"2022"},{"qus_id":"11145","year":"2022"},{"qus_id":"11508","year":"2023"},{"qus_id":"11517","year":"2023"},{"qus_id":"11630","year":"2024"},{"qus_id":"11631","year":"2024"},{"qus_id":"11658","year":"2024"},{"qus_id":"4517","year":"2016"},{"qus_id":"10202","year":"2015"},{"qus_id":"10203","year":"2015"},{"qus_id":"11955","year":"2025"},{"qus_id":"11984","year":"2025"},{"qus_id":"10360","year":"2013"},{"qus_id":"10352","year":"2013"},{"qus_id":"10333","year":"2013"},{"qus_id":"10323","year":"2013"},{"qus_id":"3625","year":"2012"},{"qus_id":"16176","year":"2011"},{"qus_id":"16204","year":"2011"},{"qus_id":"16302","year":"2010"},{"qus_id":"16433","year":"2009"},{"qus_id":"16546","year":"2008"},{"qus_id":"16550","year":"2008"},{"qus_id":"16615","year":"2008"},{"qus_id":"18151","year":"2016"},{"qus_id":"18172","year":"2016"},{"qus_id":"18679","year":"2026"},{"qus_id":"18680","year":"2026"},{"qus_id":"19125","year":"2026"},{"qus_id":"19130","year":"2026"},{"qus_id":"19171","year":"2026"}]