prep数学一题求解==学弱实在不明白也到处都找不到解答

_44_

file:///C:/Users/R/AppData/Local/Temp/msohtmlclip1/01/clip_image002.jpg
Of the 75 houses in a certain community, 48 have a patio. How many of the houses in the community have a swimming pool?
(1) 38 of the houses in the community have a patio but do not have a swimming pool.
(2) The number of houses in the community that have a patio and a swimming pool is equal to the number of houses in the community that have neither a swimming pool nor a patio.


如图，该题的答案PREP选B。。。怎么可能是B！！！怎么能够是B！！！

xenia_q

思路：Only P+P&S + Only S+Neither=75,
         Only P+P&S= 48
求P&S + Only S= ？
（1）Only P = 38，无法求Swimming Pool （因为Neither 不知）
（2）P&S = Neither
那么原等式就变成 OnlyP+P&S+OnlyS+P&S+Neither-P&S=75 就是OnlyP+OnlyS+2P&S=75,
因为OnlyP+P&S=48,所以OnlyS+P&S=75-48=27

brianmay

画个韦恩图很明显的

_44_

xenia_q 发表于 2015-8-27 15:56
思路：Only P+P&S + Only S+Neither=75,
         Only P+P&S= 48
求P&S + Only S= ？

跪谢大神。。。30号就考了感觉要没救了呢

xenia_q

_44_ 发表于 2015-8-27 16:17
跪谢大神。。。30号就考了感觉要没救了呢

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