求教：XDF陈向东的CR,P503,10

huangjinyang

A recent survey showed that 50 percent of people polled believe that elected officials should resign if indicted for a crime, whereas 35 percent believe that elected officials should resign only if they are convicted of a crime. therefore, more people believe that elected officials should resign if indicted than believe that they should resign if convicted.
the reasoning above is flawed because it
A:draws a conclusion about the population in general based only on a sample of that population
B:confuses a sufficient condition with a required condition
C:is based on an ambiguity of one of its items
D:draws a conclusion about a specific belief based on responses to queries about two different specific beliefs
E:contains premises that cannot all be true

答案选B，弄不清楚此题中神马是充分条件，神马是必要条件，求解释！

happylxm

A recent survey showed that 50 percent of people polled believe that elected officials should resign（必要条件） if indicted for a crime（充分条件）, whereas 35 percent believe that elected officials should resign（充分条件） only if they are convicted of a crime（必要条件）. therefore, more people believe that elected officials should resign if indicted than believe that they should resign if convicted.
the reasoning above is flawed because it
我是这么认为的~

hughlv

这道题应该是LSAT的吧，感觉比常规的GMAT CR要难多了。LSMM的解释我没看明白（elected officials should resign不是条件，而是结果），所以尝试以我的方式解释一次。

在分析题目前，先给个类比：50%的人认为偷东西应该枪毙，但只有35%的人认为只有在杀了人后才应该枪毙。现在你杀人了，会有多少人认为你应该被枪毙？35%吗？按实际情况，我想不是100%也应该有个90%。那这差距到底是怎么出来的呢？

问题的关键在于：50%的人认为indicted of crime是sufficient condition，而35%的人认为indicted of crime不是sufficient condition只是个定罪的required condition，convicted of crime才是sufficient condition，原因是convicted of crime只是indicted of crime的一个子集。可以推导出，认为elected officials should resign if indicted的人也认为elected officials should resign if convicted。因此持后者观点的不是35%而至少是50%+35%=85%。