题目信息

Of the 150 houses in a certain development, 60 percent have air - conditioning, 50 percent have a sunporch, and 30 percent have a swimming pool. If 5 of the houses have all three of these amenities and 5 have none of them, how many of the houses have exactly two of these amenities?

A:10

B:45

C:50

D:55

E:65

参考答案及共享解析

共享解析来源为网络权威资源、GMAT高分考生等；如有疑问，欢迎在评论区提问与讨论

正确答案： D:55

air=150*0.6=90 sun=150*0.5=75 swim=150*0.3=45

Total=air+sun+swim-1*two amenities-2*three amenities+none=90+75+45-1*two amenities-10+5=205-two amenities

205-two amenities=150

so two amenities=55

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