Q. The probability that a teacher will give an unannounced test during any class meeting is 1/5. If a student is absent twice, the probability that he will miss atleast one test, is
A) 7/25
B) 9/25
C) 16/25
D) 24/25
Explanation
(b)
Probability of student (if he miss no test)
$= \left( \ 1 - \frac{1}{5} \right) \times \left( \ 1 - \frac{1}{5} \right)$
$= \frac{16}{25}$
Hence, probability that he will miss atleast one test
$= 1 - \frac{16}{25} = \frac{9}{25}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.