袋内放入2个伍分,3个贰分,5个壹分硬币,任取5个超过金额总数超过1角的概率是多少

2025-04-14 03:15:32
推荐回答(1个)
回答1:

(C(2,2)* C(8,3)+ C(2,1)*( C(8,4)-C(5,4)- C(3,1)* C(5,3))/ C(10,5)
=(56+2*(70-5-3*10))/252
=(56+70)/252
=1/2