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 |
