A box contains 6 red, 4 white and 5 black balls. A person draws 4 balls from the box at random. Find the probability that among the balls drawn there is atleast one ball of each colour.

Explanation

`.15C_4`

A: atleast one of the ball of each color

`overlineA`: Red,White,Black

`P(overlineA)=(.^9C_4+.^10C_4+11C_4)/(.^15C_4)`

`P(A)=1-P(overlineA)`

`P(A)=1-((.^9C_4+.^10C_4+.^11C_4)/(15C_1))`.