30. 考到那个ＧＷＤ上面什么生Ａ病的人９５％会发热的那道
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
呃 这道题我看到的时候还确实画了个图。。
Fact: Asthma……is much less common ailment than hay fever……
所以灰色没有红色普及，即图中的灰色圈圈没有红色圈圈大
Fact: over 95 percent of ……asthma also……hay fever.
超过95%的灰色同时红色，即图中黄色部分占灰色圈圈的95%以上
E. The percentage of people suffering from hay fever who also have asthma is lower than 95 percent
即图中黄色的部分占红色圈圈的百分比？呵呵肯定小于95%啦
[attachimg]68145[/attachimg]
Let A = Asthma, B = fever
The condition: P(A) < P(B)
P(B|A)=0.95=P(B)/P(A&B)
Since P(A)< P(B), P(A)/P(A&B)<0.95
So P(A|B)<0.95
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