高中数学概率题红队甲乙丙与蓝队ABC篮球比赛,甲对A,乙对B,丙对C各一场,已知甲胜A,乙胜B,丙胜C的概率分别为0.4

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  • 甲乙胜 丙负的概率:0.4*0.5*0.4=0.08

    甲丙胜 乙负的概率:0.4*0.5*0.6=0.12

    甲负 乙丙胜的概率:0.6*0.5*0.6=0.18

    甲乙丙都胜的概率:0.4*0.5*0.6=0.12

    所以红队至少两名队员获胜的概率为:0.08+0.12+0.18+0.12=0.5

    ξ=0 p=0.6*0.5*0.4=0.12

    ξ=1 p=0.4*0.5*0.4+0.6*0.5*0.4+0.6*0.5*0.6=0.38

    ξ=2 p=0.08+0.12+0.18=0.38

    ξ=3 p=0.12

    故数学期望为Eξ=0*0.12+1*0.38+2*0.38+3*0.12=1.5