求解一道GWD数学题

eliasfan · 发表于 2011-1-9 21:49:05

If a committee of 3 people is to be selected from among 5 married couples so that the committee does not include two people who are married to each other, how many such committees are possible?

A.20
B.40
C.50
D.80
E.120
答案是D
而我得出的结果却是10*8*6=480
相差甚远啊，NN们能否一解释疑啊

sdcar2010 · 发表于 2011-1-9 22:16:28

480/3! = 80

The three people you selected as ABC would be the same composition as BCA, CAB, etc.

zhuang2081 · 发表于 2011-1-9 22:18:56

5对选3对， 10
然后三对里各选1个 2*2*2
10*8=80

你这种有大量重复
如1a2a3a 和2a3a1a 岂不是一样吗

eliasfan · 发表于 2011-1-10 09:39:53

3X much ,I understand

求解一道GWD数学题

所属分类: GMAT考试

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