GWD-18-Q15这道题真的有问题

fdunan

GWD-18-Q15
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

参考答案选E
但是其实有问题。把它当成数学题来做：
A: number of people with asthma only
H: number of people with hay fever only
I: number of people with both asthma and hay feve
根据题意：
A+I<H+I
I/(A+I)>95%
可知I/(H+I)<I/(A+I), but I/(A+I)>95%, so we cannot determine whether I/(H+I) < 95%. This is to say the statement that choice E must be true is wrong!
本题无正确选项。

sdcar2010

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.

sdcar2010

I/(H+I)<I/(A+I)

And 95%=I/(A+I)

Therefore, I/(H+I) < 95%

fdunan

原文是说over 95 percent, so I/(A+I)>95%, 所以e推不出来

sdcar2010

However, you cannot quantify "much lower than", can you?

I would give it as at least 50% lower.

sdcar2010

In terms of math, as long as "much lower than" is "at least 5% lower than", E) is correct.

ciciwenwen

画个韦恩图吧，30秒搞定

_Ashley

好老的贴 我也觉得这道题真的有问题
举个反例 假设一共只有100人 100人全部得了A 题目称多于百分之九十五的人得了HF 那么设定98个人得了HF
那么所有100人里，得了HF并且得了A的人一共有98个 占百分之九十八
个人见解  求NN指正

zhaokai09

_Ashley 发表于 2015-8-2 01:54
好老的贴 我也觉得这道题真的有问题
举个反例 假设一共只有100人 100人全部得了A 题目称多于百分之九十五 ...

given A/(A+I) > 95% and A < H, it is insufficient to prove A/(H+I) less than 95%.

_Ashley

zhaokai09 发表于 2015-8-2 10:54
given A/(A+I) > 95% and A < H, it is insufficient to prove A/(H+I) less than 95%.

LS跟我说的是一个意思吧   认为选项E有问题？