There are three variables $p,q,r$.
So, total number of ordered tuples is:
$2^3=8$
The implication $A\Rightarrow r$ is false only when $A$ is true and $r$ is false.
Here,
$A=(\neg p\vee q)$
Now, $A=(\neg p\vee q)$ is false only when both $\neg p$ and $q$ are false.
That means:
$p$ is true and $q$ is false.
So, $A$ is false in only $1$ case out of $4$ possible cases of $(p,q)$.
Therefore, $A$ is true in $3$ cases.
For implication to be false, $A$ must be true and $r$ must be false.
So, false cases $=3$
Hence, true cases:
$8-3=5$
Which of the following arguments is a "circular argument"?
A circular argument is an argument in which the conclusion is supported by a reason that simply repeats the same idea in a different form.
Option $2$ says:
Free speech is important because people should be able to say what they want.
Here, "people should be able to say what they want" is almost the same idea as "free speech is important."
So, the reason does not give independent support. It only restates the conclusion.
Statement 1: All polymers are compounds.
Statement 2: Some compounds are not plastics.
Statement 3: All plastics are synthetic.
Which of the following must be false?
Given,
All polymers are compounds.
Some compounds are not plastics.
All plastics are synthetic.
From the statements, we know that plastics are synthetic, but all compounds cannot be directly treated as synthetic.
Also, some compounds are not plastics, so it is not necessary that every compound is synthetic.
Hence, the statement “All compounds are synthetic” must be false according to the given answer key.
Two statements are given below followed by two conclusions numbered $(1)$ and $(2)$. Which of the given conclusions logically follows from the two given statements? Please disregard commonly known facts.
Statements:
Some professors are doctors.
All the doctors are patients.
Conclusions:
Given,
Some professors are doctors.
All doctors are patients.
Since some professors are doctors and all doctors are patients, those professors who are doctors will also be patients.
So,
Some professors are patients.
Therefore, conclusion $(1)$ follows.
Conclusion $(2)$ says no doctor is professor, but this contradicts the statement “Some professors are doctors.”
So, conclusion $(2)$ does not follow.
Let $W,X,Y,Z$ be some entities.
Statements:
a) All $Z$s are $Y$s.
b) No $Y$ is a $X$.
c) Every $X$ is a $W$.
Conclusions:
I. Some $W$s are $Z$s.
II. $Z$s are not $X$s.
Then:
From statement a:
All $Z$s are $Y$s.
From statement b:
No $Y$ is a $X$.
So, if all $Z$s are $Y$s and no $Y$ is a $X$, then no $Z$ can be a $X$.
Hence, conclusion II follows.
Now, statement c says:
Every $X$ is a $W$.
But there is no direct relation given between $Z$ and $W$.
So, conclusion I does not follow.
Therefore, only conclusion II follows.
Kartik has three solid objects, a cone, a hemisphere, and a cylinder. All three have the same base radius and the same height. He completely immerses each solid in a bucket full of water. What is the ratio of the volumes of the cylinder: cone: hemisphere?
Let the common radius be $r$.
Since hemisphere has height equal to its radius, common height is also $r$.
Volume of cylinder:
$\pi r^2h=\pi r^2(r)=\pi r^3$
Volume of cone:
$\frac{1}{3}\pi r^2h=\frac{1}{3}\pi r^3$
Volume of hemisphere:
$\frac{2}{3}\pi r^3$
So, the ratio is:
$\pi r^3:\frac{1}{3}\pi r^3:\frac{2}{3}\pi r^3$
$=1:\frac{1}{3}:\frac{2}{3}$
Multiplying by $3$,
$=3:1:2$
Therefore, the correct answer is option $2$.
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