Probability Question 155

Question: If A and B are two events such that $ P(A)\ne 0 $ and $ P(B)\ne 1, $ then $ P( \frac{{\bar{A}}}{{\bar{B}}} )= $

[IIT 1982; RPET 1995, 2000; DCE 2000; UPSEAT 2001]

Options:

A) $ 1-P( \frac{A}{B} ) $

B) $ 1-P( \frac{{\bar{A}}}{B} ) $

C) $ \frac{1-P(A\cup B)}{P(\bar{B})} $

D) $ \frac{P(\bar{A})}{P(\bar{B})} $

Show Answer

Answer:

Correct Answer: C

Solution:

$ P( \frac{\overline{A}}{\overline{B}} )=\frac{P(\overline{A}\cap \overline{B})}{P(\bar{B})}=\frac{P(\overline{A\cup B})}{P(\bar{B})}=\frac{1-P(A\cup B)}{P(\bar{B})}. $