一道费费逻辑，求牛人

594davidvilla

70. A low-pressure weather system is approaching Plainville; rainfall results from about 70 percent of such systems in the Plainville
area. Moreover, the current season, spring, is the time of year in which thundershowers, which sometimes result from low-pressure systems, are most likely to occur in Plainville.

Knowing which one of the following, in addition to the information above, would be most useful for determine the probability that Plainville will have a thundershower soon?


A.the percentage of thundershowers in Plainville that occur in the spring
B.the percentage of spring rainfalls in Plainville that are thundershowers ?
C.the percentage of thundershowers in Plainville that result from low-pressure systems
D.whether low-pressure systems in other areas are associated with rainfall
E.whether Plainville has more or fewer thundershowers each spring than do near by towns


参考答案：C

思路：文中给出两个条件，1是低压天气将到达，而70%的低压天气导致降雨，2是现在正是1年中雷阵雨最多的季节且雷阵雨有时也是由于低压天气导致；答案（C）给出了低压天气导致雷阵雨的比率，用70%乘以这个比率，就可以得到下雷阵雨的概率了。

A、B没能和低压天气联系起来，D、E为无关选项

解释不对吧，rainfall和thundershower都是低压导致的，比例怎么能相乘。因为有such systems,选项B的rainfall就和低压联系起来了。
我想知道B为什么错

199249712

为什么我的狒狒上写的这道题的答案是B？？？


额 后来想了一下。。 先感谢一下楼主啊。。不是你这个题我都不知道自己的答案是错的


我的思路是：
l/r=70
t/l=C
so t/r=70C

其中   l=low pressure
         t=thundershowers
         r=rainfall

我想错的主要原因是由于我们读错了第二句话的含义：
rainfall results from about 70 percent of such systems inthe Plainvillearea.
70%修饰的是low pressure
不是rainfall
所以比例是反的 所以可以相乘 相乘后就可以把分母消掉了

还是坐等一下NN 偶也不太确定。。

韩啸0508

C 试试这样理解，low-pre 会sometimes导致thundershower，现在有了low-pre，有多大的可能性会有thundershower呢，c回答的就是这个问题
B 春季thundershower是rain的比例并不能告诉 ， 接下来的low-pre会不会导致thundershower啊
注意直接前提

naoyixue

is the time of year in which thundershowers, which sometimes result from low-pressure systems其实文中已经把thundershower作了修饰，定义是来源低气压的， 那么，就来看那个低气压，雷雨的比例。