The total number of caps = 2 + 4 + 5 + 1 = 12 The number of ways for selecting four caps =12C1 The total number of caps other than green = 12 - 5 = 7 The number of ways for selecting four caps other than green =7C4 The probability of selecting four caps and none of them are green
P(A′)=
The number of ways for selecting four caps other than green aps