There are three boxes. Box 1 contains one white ball and two
black balls; box 2 contains two white balls and one black ball; box 3 contains two white
balls and two black ones. Someone selects one ball randomly from each box. So totally,
three balls are taken out from three boxes. Find the probability that there are exactly one
white ball among selected 3 balls.
Stats hw question?
2015-10-16 12:44 am
回答 (1)
2015-10-16 10:44 am
✔ 最佳答案
Box 1 : ○●●Box 2 : ○○●
Box 3 : ○○●●
N1 = n( ○ form box 1 ) * n( ● form box 2 ) * n( ● form box 3 ) = 1*1*2 = 2
N2 = n( ○ form box 2 ) * n( ● form box 1 ) * n( ● form box 3 ) = 2*2*2 = 8
N3 = n( ○ form box 3 ) * n( ● form box 1 ) * n( ● form box 2 ) = 2*2*1 = 4
P(○●●)
= ( N1 + N2 + N3 ) / (3*3*4)
= ( 2 + 8 + 4 ) / 36
= 14/36
= 7/18 ..... Ans
收錄日期: 2021-05-02 14:18:24
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