A box contains `15` green and `10` yellow balls. If `10` balls are randomly drawn, one-by-one, with replacement, then the variance of the number of green balls drawn is : (a) `12/5` (b) `6` (c) `4` (d) `6/25`

A. `(12)/(5)`

B. 6

C. 4

D. `(6)/(25)`

A. `(12)/(5)`

B. 6

C. 4

D. `(6)/(25)`

Correct Answer – A

Given box contains 15 green and 10 yellow balls.

`:. Total number of balls `=15+10=25`

P(green balls)=`(15)/(25)=(3)/(5)`=p=Probability of success

P(yellow balls)`=(10)/(25)=(2)/(5)=q`=Probability of unsuccess and n=10=Number of trials.

`:. “Variance” =npq=10xx(3)/(5)xx(2)/(5)=(12)/(5)`