There are 12 white and 12 red ball in a bag. Balls are drawn one by one with replacement from the bag. The probability that 7th drawn ball is 4th white, is

Options

A. `1//4`
B. `5//32`
C. `3//16`
D. `5//16`

Answer

B

Explanation

We have,
`P=` Probability of getting a white ball in a draw `=1//2`
`q=` Probability of getting a red ball in a draw `=1//2`
Getting `4th` white ball in `7th` draw means that, we must get 3 white balls in the first six draws and a white ball in `7th` draw.
`therefore` Required Probability `={.^6C_(3)((1)/(2))^3((1)/(2))^(6-3)}xx(1)/(2)=(5)/(32)`