TTGWD20-19

這題沒search到 請nn幫我看看我哪裡做錯了

Q19:

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

我的做法是

let 1996 car be X, 1996 truck be Y, then 1997 car = 0.89X, 1997 truck = 1.07Y

(0.89X + 1.07Y) = 1.01(X + Y) solve and get

0.12X = 0.07Y, X/Y = 7/12 ==> 7:12

不知道是哪裡想錯了呢

只是你解到最后算错了……

最后那个是0.12X = 0.06Y，不是0.12X = 0.07Y

所以是1：2

天啊 想趕快去挖個洞躲起來 真的輸給自己了

多謝好心人的指點