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标题: GWD-9-Q13 [打印本页]

作者: modernre 时间: 2012-5-17 06:54 标题: GWD-9-Q13

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.

正确答案是E。可是我很菜，不知道怎么得出来的。望高手解答！非常感谢！！！

作者: Quadrifolia 时间: 2012-5-17 21:45

This is a must-be-true question: inference.

Only E is true becasuse A is less common than HF.  Therefore the total

number of people who have HF is bigger than that of who have A.  Then it

is a simple math problem to calculate the percentages for comparison.

Two hundred people have hay fever.  One hundred people have asthma. Out

of the 100 people who have asthma, 95 of them have hay fever, in other

words, 95% of the people who have asthma also have hay fever.

Then out of the 200 people who have hay fever, again 95 of them have

asthma.  Translation: only 47.5% of the people who have hay fever also

have asthma.

Simple math.

作者: avagmat 时间: 2012-5-22 06:35

假设有A人得了Asthma B人得了hay fever 然后由题干知道0.95A是两种病都得了的。。。那么两种病都得了的人在B占的比例是0.95A/B 然后由题干知道A<B 所以0.95A/B<0.95

作者: modernre 时间: 2012-5-22 19:35

哈哈，谢谢啦~~

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