[讨论]对《费费逻辑宝典》详解版第70题解释的疑问

gisbbl

宝典对第70题的解释如下：

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

我感觉答案是B，想了半天没想通是C。又查了CD，发现讨论的答案也是B。请参见贴子：

http://forum.chasedream.com/dispbbs.asp?BoardID=24&replyID=182290&id=25030&star=1&skin=0

请确认一下答案好吗？

lawyer_1

B

原文：1。LOW-PRESSURE的70%可能性有RAINFALL

           2。目前正是LOW-PRESSURE

所以，如果RAINFALL是thundershowers的可能性知道的话，就可知道thundershowers的可能性了

C错，C的意思为：thundershowers中有多少比例由low-pressure造成的。如果改为low-pressure有多大可能导致thundershowers，则为答案

[此贴子已经被作者于2004-7-13 22:42:38编辑过]

gisbbl

Thanks!

那么论坛里新编的《费费逻辑宝典》详解版的70题解释有错误,请编者改正.

lawyer_1

我查了费费逻辑宝典的没有解释的版本，答案为B。祥解版的解释是将PERCENTAGE理解成修饰LOW-PRESSURE。应该是错的。就像原文的这句话rainfall results from about 70 percent of such systems in the Plainville area。他的意思为低压系统的70%可能性会导致rainfall, 如果70 percent of 放到rainfall，则意思变为：70%的rainfall是低压造成的。两个意思不同。

alexmuir

牛！！！

tony6

顶一下

singdeath

    

Lawyer 很细心，读题很透彻啊！

    

天蝎座1107

其实感觉这道题就像是用概率的思维去做一样

daisyliuliu

对lawyer很崇拜！
这一题我也有疑问。
先说C，文中说'which sometimes result from low-pressure systems'，是不是意为还有相当一部分thundershowers不是low-pressure system造成的? 如果是，那么就证明C推出的概率不准确。
而B中的计算方式是P（thundershower）=P(lower pressure systems)*P(rainfall)*P(rainfall that are thundershowers)=100%*70%*(rainfall that are thundershowers).所以B为答案。

请牛牛指教，这样推合理吗？

solde

终于找到正确答案了！必须顶一下啊！