Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Probability

Question:

If $P(A ∩ B)=\frac{1}{2}, P(\overline{A} ∩ \overline{B})=\frac{1}{2}$ and $2P(A)=P(B)=p$, then the value of p is equal to

Options:

$\frac{1}{2}$

$\frac{2}{3}$

$\frac{1}{4}$

$\frac{1}{3}$

Correct Answer:

$\frac{2}{3}$

Explanation:

We have,

$P(A ∩ B)=\frac{1}{2}, P(\overline{A} ∩ \overline{B})=\frac{1}{2}$ and $ 2P(A)=P(B)=p$

Now, $ P(\overline{A} ∩ \overline{B})=\frac{1}{2}$

$⇒ P(\overline{A ∪ B})=\frac{1}{2}$

$⇒ 1- P (A ∪ B) =\frac{1}{2}$

$⇒  P (A ∪ B) =\frac{1}{2}$

$⇒P(A) +P(B)- P(A ∩ B)=\frac{1}{2}$

$⇒ \frac{p}{2} +p -\frac{1}{2}=\frac{1}{2}⇒ \frac{3p}{2}=1⇒p=\frac{2}{3}$