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?
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方法一：所有组合减去有couple的组合＝C(10,3)-C(5,1)*C(8,1)=80. 有couple的组合＝先从5对couple选一对，已经有两个人了，再从剩下8个人里选一个。 方法二：先从5对夫妻里面选3对，再从这3对夫妻里每对各自选一个人出来。C(5,3)*C(2,1)*C(2,1)*C(2,1)=80
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方法一：所有组合减去有couple的组合＝C(10,3)-C(5,1)*C(8,1)=80. 有couple的组合＝先从5对couple选一对，已经有两个人了，再从剩下8个人里选一个。
方法二：先从5对夫妻里面选3对，再从这3对夫妻里每对各自选一个人出来。C(5,3)*C(2,1)*C(2,1)*C(2,1)=80
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