求助啊~~~~~~~~~

niqi119 · 发表于 2013-2-22 02:39:56

From a group of 3 boys and 3 girls, 4 children are to be randomly selected. What is the probability that equal numbers of boys and girls will be selected?

A.   1/10
B.    4/9
C.    1/2
D.    3/5
E.    2/3
跪求方法，谢谢啦

EMMALIULIU · 发表于 2013-2-22 09:03:25

随机挑选4人挑法：C(4,6)=15
两男两女挑法：C(2，3)*C(2，3)=9
所以答案是：9/15=3/5

求助啊~~~~~~~~~

所属分类: GMAT考试

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