PP-T2-PS91

[Huang Hsin-Yi]

91. 10146-!-item-!-187;#058&007291
A certain car averages 25 miles per gallon of gasoline when driven in the city and 40 miles per gallon when driven on the highway. According to these rates, which of the following is closest to the number of miles per gallon that the car averages when it is driven 10 miles in the city and then 50 miles on the highway?

(A) 28
(B) 30
(C) 33
(D) 36
(E) 38

Ans:D

[小花]

(10*25+50*40)/10+50=37.5


怪了 應該是E 我當初怎麼楜裏糊塗選對了?

[Huang Hsin-Yi]

對阿,我也是算你那個數字

[gman]

我有另外一個想法 支持 D
不知道是我的思路有問題還是怎樣 XD
我的列式

Total gallon = (10/25+50/40) = 33/20
Total miles = 60
miles per gallon = 60/ (33/20) = 400/11 = 36.3 ==> D

[小花]

我有另外一個想法 支持 D
不知道是我的思路有問題還是怎樣 XD
我的列式

Total gallon = (10/25+50/40) = 33/20
Total miles = 60
miles per gallon = 60/ (33/20) = 400/11 = 36.3 ==> D

請教一下 gman大大的思路