PP-T1-DS-2

[pauline_chiou]

2. 142-!-item-!-187;#058&000140
Of the students who eat in a certain cafeteria, each student either likes or dislikes lima beans and each student either likes or dislikes brussels sprouts. Of these students, 2/3 dislike lima beans; and of those who dislike lima beans, 3/5 also dislike brussels sprouts. How many of the students like brussels sprouts but dislike lima beans?

(1) 120 students eat in the cafeteria.

(2) 40 of the students like lima beans.

答案是D(我選A)
後來想想(2)也可以得知dislike lima beans

有點卡住..不知道該怎麼反推回去比例....How many of the students like brussels sprouts but dislike lima beans

[Huang Hsin-Yi]

版主有教,遇這種題,就劃 2個圈圈一個長方型 就很好解(詳情請看og p118, P144)
條件:1/3 like bean ,2/3*3/5 both hate, 2/3*2/5 only like sprouts
(1)x=120 可求出個條件 填進上述圖型 got ans:40
(2) 1/3x=40 x=120 同理

ANs:D

[pauline_chiou]

感謝~~看來基本功夫要再加強.....