Q. The chances to fail in physics are 20% and the chances to fail in mathematics are 10%. What are the chances to fail in at least one object?
A) 28%
B) 38%
C) 72%
D) 82%
Explanation
(a)
Let $P(A) = \frac{20}{100} = \frac{1}{5},\ P(B) = \frac{10}{100} = \frac{1}{10}$
Since, events are independent and we have to find
$P(A \cup B) = P(A) + P(B) - P(A).P(B)$
$= \frac{1}{5} + \frac{1}{10} - \frac{1}{5}.\frac{1}{10}$
$= \frac{14}{50} \times 100 = 28\%$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.