53、DS：in an organization, 60% people engaged in research, 54% people engaged in counseling, 30% engaged in teaching. Question: what percent of people in organization engaged in at least two fields? 1) half of the people who engaged in teaching attend at least two field 2) 20% people of whole organization who engaged in at least two field do not engaged in teaching 貌似是这样30% in teaching绝对肯定 两个条件也肯定，答案我好像选C，但不知对不对。
19、PS：说一个slink(貌似这么拼写的),由drink + toppling组成。然后说一种slink,可以从one of two crafters, 2 available of 8 toppling and 1 of 3 drinks 挑选组合而成. Only same toppling and same drink can consider as one type of slink. 问有多少种不同的slinks: 1份套餐=2个toppling+1个crafter+1个drink组成，t从8个里选2个，c从2个里选1个，d从3个里选一个，排列组合为C(8,2)*C((2,1)*C(3,1)=168。但只有相同的T和D才叫同一类的S,那么忽略c对种类的影响 直接8选2乘以3选1， 28×3=84
20、维恩图。DS 有40同学学习French, 30个学Spanish，20个选Chinese,问有多少人exactly 学2门语言: 1) 有5个人学3门语言 2) 52 students study at least one of the three languages. F=40(学习French的人）,S=30（学习Spanish的人）,C=20（学习Chinese的人） I=F+S+C-FS-SC-FC+FSC 1）FSC=5（三门语言都学的人） 2）I=52（至少学习一门语言的人，i.e.学习一门语言，学习两门语言，学习三门语言人数的总和，所以是全集） 1）& 2）可以求出FS+SC+FC,即只学习两种语言的人。选C。
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发表于 2009-11-9 13:43:26
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