JEE Main On 8 April 2017 Question 29
Question: Three persong P, Q and R independently try to hit a target. If the probabilities of their hitting the target are $ \frac{3}{4},\frac{1}{2} $ and $ \frac{5}{8} $ respectively, then the probability that the target is hit by P or Q but not by R is : [JEE Online 08-04-2017]
Options:
A) $ \frac{39}{64} $
B) $ \frac{21}{64} $
C) $ \frac{9}{64} $
D) $ \frac{15}{64} $
Show Answer
Answer:
Correct Answer: B
Solution:
- $ ( \frac{3}{4} )( \frac{1}{2} )( \frac{3}{8} )+( \frac{1}{4} )( \frac{1}{2} )( \frac{3}{8} )+( \frac{3}{4} )( \frac{1}{2} )( \frac{3}{4} ) $ $ =\frac{12+9}{64} $ $ =\frac{27}{64} $
