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.

第一个fact 说 hay fever 比asthama 普遍

第二个fact 说 得asthma的患者中超过95%同时患有hay fever

就凭这两点，怎么就能推出患有hay fever的患者中同时患有asthma的少于95%？这里的分母是患有hay fever的患者总和，而不是fact II中的患有asthma的患者总和，不是吗？

忘指点迷津~~

哦，是不是要这样推：

Fact II

同时得asthma & hay fever的人数/得asthma的人数〉95%

且 得asthma的人数< 得hay fever的人数

推出

同时得asthma & hay fever的人数/得hay fever的人数 < 95%

分子相同，分母变大

跟你基本一样，就是一个大范围和小范围包含的意思

MM，你是对的

我的方法是作图：

画两个相交的圆，大圆－得hay fever的人；小圆－得asthma的人，公共部分占小圆95％，

可见，公共部分占大圆必小于95％