问题求助

Ibelive · 发表于 2007-2-27 12:30:00

set A,B,C have soem elements in common. if 16 elements are in both A and B, 17 elements are in both A and C, and 18 elements are in both B and C, how many elements do all three of the sets A, B, and C have in common?

1) of the 16 elements that are in both A and B, 9 elements are also in C

2) A has 25 elements, B has 30 elements, and C has 35 elements.

the answer is A. why?

YY_lalala · 发表于 2007-2-27 19:14:00

1）16个同时属于A和B，其中又有9个还属于C ＝> 同时属于ABC的即为9个

你的具体问题是什么呢？

Ibelive · 发表于 2007-2-27 22:43:00

为什么B不可以呢?

YY_lalala · 发表于 2007-2-27 23:19:00

全集＝A并B并C＝A+B+C-A交B－A交C－B交C＋A交B交C

题目要求“A交B交C”

题干和2）条件没有给出全集为多少，所以还是求不出来

问题求助

问题求助

所属分类: GMAT考试

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