AMC8 1998

AMC8 1998 · Q14

AMC8 1998 · Q14. It mainly tests Percent.

At Annville Junior High School, 30% of the students in the Math Club are in the Science Club, and 80% of the students in the Science Club are in the Math Club. There are 15 students in the Science Club. How many students are in the Math Club?

在 Annville 初中，数学俱乐部 30% 的学生在科学俱乐部，科学俱乐部 80% 的学生在数学俱乐部。科学俱乐部有 15 名学生。数学俱乐部有多少学生？

(A) 12 12

(B) 15 15

(D) 36 36

(E) 40 40

Answer

Correct choice: (E)

正确答案：（E）

Solution

Answer (E): Since 80% of the Science Club members are also in the Math Club, there are $0.8(15)=12$ students common to both clubs. Because 30% of the students in the Math Club are also in the Science Club, there are $12\div 0.3=40$ students in the Math Club.

答案（E）：由于科学俱乐部成员中有 80% 同时参加数学俱乐部，所以两者共有的学生人数为 $0.8(15)=12$。又因为数学俱乐部学生中有 30% 也参加科学俱乐部，所以数学俱乐部的学生人数为 $12\div 0.3=40$。

Topics

AR.003 Percent