[(7x6x5x4x3)÷(5x4x3x2x1)]÷[(31x30x29x28x27x26x25)÷(7x6x5x4x3x2x1)]x100%
=42÷253921x100%
=0、01654%
发表于:2020-04-26 14:58:59 浏览:1230次
[(7x6x5x4x3)÷(5x4x3x2x1)]÷[(31x30x29x28x27x26x25)÷(7x6x5x4x3x2x1)]x100%
=42÷253921x100%
=0、01654%
31选7选中3个数字有c(7,3)
=35种全中概率
=1/c(31,7)
=3.8*10^(-7)36选7选中3个数字c(7,3)
=35种全中概率
=1/c(36,7)
=1.2*10^(-7)
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