Question

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)`

Answer 1

Correct Answer - A
Let X denote the number of green balls in a draw 10 balls one-day one with replacement. Then,X is a binomial variate with
`n=10,p=(15)/(25)=(3)/(5)and q=(2)/(5)`
`therefore` Variance `X=npq=10xx(3)/(5)xx(2)/(5)=(12)/(5)`.