作者chestnut42 ()
看板GMAT
标题[Q. ] 请问一题GWD题目
时间Fri Dec 29 07:44:13 2017
Of the 32 students in a certain class, 15 are in a music club and 20 are
in a dance club. If 10 of the students are not in either club, how many of
the students are in only one of the two clubs?
A. 5 B. 9 C.10 D. 17 E. 25
如果设两个社团都都参加为X
15+20-X+10=32, X=13
请问只参加一个社团的人数的算法用两者联集减掉交集
15+20-13=22是哪里出了问题呢?
谢谢
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※ 编辑: chestnut42 (111.249.17.11), 12/29/2017 07:45:39
1F：推 liu1991: 应该是(15-13)+(20-13)=9 12/29 08:09
2F：推 wakamala: 15+20-13是两个社团的人减掉重复计算的人, 所以两个社团 12/29 09:02
3F：→ wakamala: 都参加的人还是有包含在内 12/29 09:03
4F：→ chestnut42: 感谢楼上两位的解说 12/30 00:48