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2010-01-17 22:52 来自版块 -
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yiyiyi31876:
2.若为两种卡片(1)1张--4张 (C32)*(C21)*(C51)*(1/3)*(1/3)的4次方=10/81
(2)2张--3张 (C32)*...(2010-01-17 23:30)
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wq63121859:
选D 先算不中奖的概率:1.若全为一种卡片 3*(1/3)5次方=1/81
2.若为两种卡片(1)1张--4张 (C32)*(C21)*(C51)*(1/3)*(1/3)的4次...(2010-01-17 23:22)
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jilei1:
老师,我也没看懂~~~~~~~(2010-01-17 23:18)
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yiyiyi31876:
为什么要减3啊!(2010-01-17 23:17)
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teacherM:
解答:
[ 本帖最后由 teacherM 于 2010-1-17 23:05 编辑 ](2010-01-17 23:02)
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yiyiyi31876:
对,怎么做的啊?(2010-01-17 22:59)
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NN457975063:
能不能选D啊?(2010-01-17 22:57)
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