求助GWD1-33

kenlily

Q33:

At a certain school, the ratio of the number of second graders to the number of fourth graders is 8 to 5, and the ratio of the number of first graders to the number of second graders is 3 to 4. If the ratio of the number of third graders to the number of fourth graders is 3 to 2, what is the ratio of the number of first graders to the number of third graders?

A. 16 to 15

B. 9 to 5

C. 5 to 16

D. 5 to 4

E. 4 to 5

periodic

二：四 = 8：5 ------（1）

一：二 = 3：4 ------（2）

三：四 = 3：2 ------（3）

问：一：三 = ？

很容易啊！！

（1）/（3）= 16/15 = 二：三 -----（4）

（2）*（4）= 48/60 = 4/5 = 一：三....即为答案~~~选E

kenlily

thanks a lot!我错用了代入法，所以走迷宫了！