GWD12(DS)-12

[kikisky]

What was the percent increase in the average (arithmetic mean) contribution per member of a certain public radio station from 1985 to 1995 ?
(1)Total contributions by members increased from $505,210 in 1985 to $1,225,890 in 1995.
(2)The number of members exactly doubled from 1985 to 1995.

答案是(C)
為什麼不是(E)?就算兩個條件合併了也沒有member的數字
那percent也算不出來吧???

[homaru]

可以啊
假設1985有10個人
每人出:
1985:505210/10=50521
1995:1225890/20=61294.5

percent increase per member=(61294.5-50521)/50521=0.213...=21.3%
你用100個人代進去算答案也一樣
只要知道人數增加比例就行

[asicschu]

homaru 真是好樣的! :)

[吳志道]

概念1985 X人 1995 2x人

[1225890/2x - 505210/x]/ 505210/x

X可以約分 考百分比題目時..要注意可約分的未知數 ^^

[Grace]

謝謝吳兄細心提醒...

[chris8888]

yeah, 考是時候還是要仔細的做出方程式, 很多時候是可以約掉的. 並非就真的算不出來.