jk139
春芽
共回答了20个问题采纳率:100% 举报
(1)4名选手均为男选手的概率=[C2(2)/C5(2)]*[C3(2)/C4(2)]=(1/10)*(3/6)=1/20
(2)x的可能值为0、1、2、3.
P(x=0)=1/20
P(x=1)=[C2(1)*C3(1)/C5(2)]*[C3(2)/C4(2)]+[C2(2)/C5(2)]*[C3(1)*C1(1)/C4(2)]
=(2*3/10)*(3/6)+(1/10)*(3*1/6)
=7/20
P(x=2)=[C2(1)*C3(1)/C5(2)]*[C3(1)*C1(1)/C4(2)]+[C3(2)/C5(2)]*[C3(2)/C4(2)]
=(2*3/10)*(3*1/6)+(3/10)*(3/6)
=9/20
P(x=3)=[C3(2)/C5(2)]*[CC3(1)*C1(1)/C4(2)]=(3/10)*(3*1/6)=3/20
分布列为:
x 0 1 2 3
P 1/20 7/20 9/20 3/20
E(x)=0*(1/20)+1*(7/20)+2*(9/20)+3*(3/20)=1.7
1年前
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