求解GWD题~ 感谢！

nikkoyu

1.If a committee of 3 people is to be selected from among 5 married couples so that the committee does not include two people who are married to each other, how many such committees are possible?


A.20       B.40         C.50       D.80        E.120

2.At a certain company, 25 percent of the employees are male and 50 percent of the employees are sales staff.What is the number of employees at this company?
(1)Exactly 7 of the employees at the company are males who are sales staff.
(2)There are 16 more female employees than male employees at the company.
答案为B？

3.In a survey of 200 college graduates, 30 percent said they had received student loans during their college careers, and 40 percent said they had received scholarships.What percent of those surveyed said that they had received neither student loans nor scholarships during their college careers?
(1)25 percent of those surveyed said that they had received scholarships but no loans.
(2)50 percent of those surveyed who said that they had received loans also said that they had received scholarships.

为什么答案选D而不是A？

请各位帮忙解释一下？

Leliolevine

是小灰灰啦。。灰太狼他儿子。^_^

非常感谢灰太狼，我明白了，谢谢！

-- by 会员 nikkoyu (2010/8/31 8:53:27)

nikkoyu

非常感谢灰太狼，我明白了，谢谢！

Leliolevine

1、五对夫妇中选三个人，任何两个都不是夫妇。先从五对里面选三对，再从三对里面分别选一个。。5C3*2*2*2=80
2、25%是男人，50%是销售员。（1）不知道同时是男人和销售员的人数，所以不能得出总的雇员人数。（2）女人比男人多16个，就是75%*x-25%*x=16  可以求出总的雇员人数。  故选B
3、200个学生，30%贷款，40%有奖学金。问既没有贷款又没有奖学金。（1）25%只有奖学金没有贷款，可得知15%既有奖学金又有贷款，15%只有贷款没有奖学金。所以既没有奖学金又没有贷款100%-25%-15%-15%=35%
（2）50%贷款的人说他们也有奖学金，就是指既有贷款由有奖学金有15%，则可知15%只有贷款没有奖学金，25%只有奖学金没有贷款，算出来既没有奖学金有没有贷款的也是35%。