Fact: Asthma, a bronchial condition, is much less common ailment than hay fever, an allergic inflammation of the nasal passages.

Fact: over 95 percent of people who have asthma also suffer from hay fever.

If the information given as facts above is true, which of the following must also be true?

A.   Hay fever is a prerequisite for the development of asthma

B.    Asthma is a prerequisite for the development of hay fever

C.   Those who have neither hay fever nor asthma comprise less than 5 percent of the total population

D.   The number of people who have both of these ailments is greater than the number of people who have only one of them

E.    The percentage of people suffering from hay fever who also have asthma is lower than 95 percent.

答案是E 我选的是B 每次一看到这种有数字的就晕......

望NN指教

题目类型：归纳

 Asthma< hay fever

 95% of Asthma has hay fever

 b. 题目说有asthma 才会有hay fever 但是因为 people who got hay fever > people who got asthma 所以错

 E. 在有hay fever的人中 有asthma 的人少于95% 

 可以这么想，既有HAY FEVER 又有 Asthma的人数是一定的设为m吧

 m除以asthma=95%  因为asthma<hay fever

 m除以hay fever<95%

 不知这么说对不对...

C是无关选项.这题里的95%是得asthma的人中有95%的人也有hay fever,而total population这个概念根本没在题目里出现.所以C里这个” less than 5 percent of the total population”根本无从谈起.

这题目其实就是两个变量一个交集.假设得asthma的人有A,得hay fever的人有H,

FACT 1  ->  A < H

Fact 2  -> A.H的交集相当于95%A

这部分交集占据H的比例为 95%A / H

因为 H>A 所以 95%A / H肯定小于95%,就是两种病都有的人占hey fever病人的比例肯定小于 95%.