Exp. (a)
Given box contains 15 green and 10 yellow balls.
∴ Total number of balls =15+10=25
P( green balls )=2515​=53​=p= Probability of success
P( yellow balls )=2510​=52​=q= Probability of unsuccess
and n=10= Number of trials.
∴ Variance =npq=10×53​×52​=512​