标题: 问一道旧prep12题 [打印本页] 作者: crocdile 时间: 2010-7-22 21:59 标题: 问一道旧prep12题 Finding of a survey of Systems magazine subscribers: Thirty percent of all merchandise orders placed by subscribers in response to advertisements in the magazine last year were placed by subscribers under age thirty-five.
Finding of a survey of advertisers in Systems magazine: Most of the merchandise orders placed in response to advertisements in Systems last year were placed by people under age thirty-five.
For both of the findings to be accurate, which of the following must be true?
(A) More subscribers to Systems who have never ordered merchandise in response to advertisements in the magazine are age thirty-five or over than are under age thirty-five. (B) Among subscribers to Systems, the proportion who are under age thirty-five was considerably lower last year than it is now. (C) Most merchandise orders placed in response to advertisements in Systems last year were placed by Systems subscribers over age thirty-five. (D) Last year, the average dollar amount of merchandise orders placed was less for subscribers under age thirty-five than for those age thirty-five or over. (E) Last year many people who placed orders for merchandise in response to advertisements in Systems were not subscribers to the magazine.
这个题说，subscribers中间有30%的人是under 35,而总人中有most也就是大于50%的人是under 35，那不是说明不是subscribers 又place merchandise orders 有大于30%的人是under 35 的吗？为什么题目答案e说没定杂志的人中place orders of merchandise 的人多？这有什么关系啊？不理解，请大牛们给指点指点作者: wangsiwei 时间: 2010-7-22 23:35
我觉得吧，你可以用韦恩图想想 subscribers & under age thirty-five = 30% A (假设A＝subscriber) under age thirty-five >=50% B (假设B＝total） B>A 所以30％ A < 50% B 所以 一定有不是subscribers 下order的。E里面没有说多，只是说有这样的人。作者: crocdile 时间: 2010-7-23 11:37
啊，原来是这样，谢谢谢谢