GMAT/留學申請專業顧問 Donz 之資訊交流園地

 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

    Solution:

    Percent 和 Fraction 其實就跟修辭一樣

    x percent of A be (V) .......(by B)
    所以 x% = A & B / B

    25 percent of those who are married are self-employed
                                  ^^^^^^^^^^^^^^          ^^^^^^^^^

    25% = married & self-employed / married

    所以應該是 156 * 25% = 39
    70 - 39 = 31    31/248 = 1/8

    Answer: (A)