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标题: 求助OG数学题。关于完全否定与部分否定不会区分，导致概率求错 [打印本页]

作者: huangsiyan 时间: 2011-3-20 08:05 标题: 求助OG数学题。关于完全否定与部分否定不会区分，导致概率求错

In a nationwide poll, N people were interviewed. If 1/4 of them answered “yes” to question 1, and of those, 1/3 answered “yes” to question 2, which of the following expressions represents the number of people interviewed who didn’t answer yes to both questions?

正确答案是1-1N/4*3N/4=11N/12

看到答案才知道是求没有两道题同时答YES的人数。

而之前自己的理解是didn’t answer yes to both questions = 对两道题都没有答yes，也就是说对两道题都答了NO

由于题意理解错误，就不知道怎么算……

忘大虾指点，怎么判断这种否定到底是完全否定还是部分否定

作者: templars 时间: 2011-3-21 06:52

people interviewed who didn’t answer yes to both questions are the people who answered No to both questions or answered no to only one of the questions.

Answer yes to both question means Yes for 1 and Yes for two.

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