OG数学一道题 请大家看看~~看不懂啊

littlebluesks

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 expression represents the number of people interviewed who did not answered "yes" to both questions.
(A) N/7
(B) 6N/7
(C) 5N/12
(D) 7N/12
(E) 11N/12

答案是E 我看解释当中写了1/3*(1N/4)表示对两道题目均回答了"Yes"的人，但是为什么我就是像不明白这个式子表示这个呢，不是应该表示对第二道题目回答了"Yes"的人吗？

cherryserena

1/4 of 所有人答对了第1题   1/3 of 所有人答对了2题  相乘就是两道都答对了的啊

mermaid2011

If 1/4 of them answered "yes" to question 1,and of those,1/3 answered "yes" to question 2.

就是说1/4里面的1/3对第二题答了YES，也就是只有1/12对两题都YES了...也就是剩下11/12没有都YES两道题...

不知道这样表述楼主可理解...

bastencool

这道题我终于想明白啦~~~and of those，指的应该是1/4里面的1/3回答第二个问题为yes，即第二个包含在第一个内，即1/4*1/3的人both answered yes!,最后减一下就对啦！是不是~~~~~~~~~

littlebluesks

恩...这样理解的话我懂了 但是也太咬文嚼字拉这个题目