Re: [計量] If a bowl contains seven marbles ...
※ 引述《ELASTOMER (惡性循環........)》之銘言：
題目是
If a bowl contains seven marbles, three red and four
green, four marbles are drawn from the bowl at random
without replacement. What is the propability that contains
two red marbles and two green ones?
答案是18/35 不知要怎麼解,麻煩各位幫我解答一下,謝謝
C(3,2) x C(4,2) 3*6 18
所求= _____________________ = ___________ = _____
C(7,4) 7*5 35
C(7,4)=從七個彈珠中選四個彈珠(題目說不放回去)
C(3,2)=三個紅彈珠中要隨選兩個出來組合
C(4,2)=四個綠彈珠中要隨選兩個出來組合
應該是這樣吧^^
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※ 編輯: nehsband 來自: 140.112.243.79 (10/13 23:51)
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