Q. A dice is thrown 100 times, getting an even number is considered a success. The variance of the number of successes is
A) 10
B) 25
C) 18
D) 10
Explanation
(b)
Let $E =$Event of getting an even numbers
$= \{ 2,4,6\}$
$n(E) = 3$
$\therefore$ Probability of success, $P = \frac{3}{6} = \frac{1}{2}$
and probability of failure, $q = \frac{1}{2}$
$\therefore$ Variance$= npq = 100 \times \frac{1}{2} \times \frac{1}{2} = 25$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.