167.
In a survey of 248 people, 156 are married, 70 are self-employed, and 25
percent of those who are married are self-employed. If a person is to be
randomly selected from those surveyed, what is the probability that the
person selected will be self-employed but not married?
(A) 1/8
(B) 4/31
(C) 117/248
(D) 1/4
(E) 31/117
答案是A = =
我算出來的答案是1/31 我真的想不透.....
我的算法是全體為248 25% married and self-employed 的人數為62
70-62=8 這是be self-employed but not married的人數
8/248=1/31 這是被抽中的機率。
結果沒這答案= = 哪裡出錯了= =
懇請高手指點
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 59.121.37.64
推
04/05 17:10, , 1F
04/05 17:10, 1F
→
04/05 17:25, , 2F
04/05 17:25, 2F
討論串 (同標題文章)