GWD22-Q32

dabiaoxun

	Number Studying	Number Not	Total
	Biology	Studying Biology
Number			18
of Boys
Number
of Girls
Total	26

The table above shows the number of students in a certain high school class who are boys and the number of students in the class who are studying biology.  What is the total number of students in the class?

(1)   Of the boys in the class, 15 are studying biology.

(2)   The number of girls in the class is twice the number of students in the class who are not studying biology.

                  

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

求助解题思路. 答案选的是B﹐我选C. Thanks!!!

robert

假设男生没学biology的为b2个人，女生没学biology的为g2个人，则有

1)b1+b2=18

2)g1+g2=2(b2+g2)

3)b1+g1=26

求的是b1+b2+g1+g2

3)-1)得出 g1-b2=8

把g1-b2代入2)得 b2+g2=8

所以b1+b2+g1+g2=8+26=34

sinadragon

同意robert

nikema

我认为你选的答案正确。应该是 C。  单独的 B给的条件求不出来。

小腾

B is sufficient..

Assuming that the number of students in the class who are NOT studying

biology is X, then the number of girl in the class is 2X.

18+2X=26+X ..so X can be solved.