Q34

A certain company that sells only cars and trucks reported that revenues from car sales in 1997 were down 11 percent from 1996 and revenues from truck sales in 1997 were up 7 percent from 1996. If total revenues from car sales and truck sales in 1997 were up 1 percent from 1996, what is the ratio of revenue from car sales in 1996 to revenue from truck sales in 1996?

A. 1 : 2

B. 4 : 5

C. 1 : 1

D. 3 : 2

E. 5 : 3

我看完題目後知道是a,b其中之一,但是不懂解.

设96car revenue为X,96 truck revenue为Y

则97car revenue为0.89X,97 truck revenue为1.07Y

(0.89X+1.07Y)/(X+Y)=1.01

求X/Y

(0.89X+1.07Y)/(X+Y)分数上下同除以Y,得出(0.89X/Y+1.07)/(X/Y+1)=1.01

从而解出X/Y=1:2

(0.89X+1.07Y)/(X+Y)分数上下同除以Y,得出(0.89X/Y+1.07)/(X/Y+1)=1.01

从而解出X/Y=1:2