Question

袋中10个乒乓球,3黄7白,不放回的依次拿取,请问拿到3黄,2黄1白,1黄2白,3白的概率分别是多少

Answer 1

3黄的概率：C(3,3) / C(10,3) = 1/120

2黄1白的概率：C(3,2)*C(7,1)/C(10,3) = 21/120 = 7/40

1黄2白的概率：C(3,1)*C(7,2)/C(10,3) = 63/120 = 21/40

3白的概率：C(7,3)/C(10,3) = 35/120 = 7/24

四种情况的概率相加正好是1.

希望有用～