A bag contains 3 red, 5 yellow and 4 green balls. 3 balls are drawn randomly. What is the probability that the balls drawn contain exactly two green balls ?

Explanation

Total no. of balls = 12
n (S) = `^12C_3`=(12 xx11xx 10)/ (3 xx 2)`
= 220 green balls can be selected from 4 green balls in 4C2 ways and the rest one ball can be selected from the remaining (12 – 4) = 8 balls in `^8C_1`ways.
`n (E) = ^4C_2 × ^8C_1 = 6 × 8 = 48`
`therefore P(E) =48/220 = 12/55`