Alice's take-home pay last year was the same each month, and she saved the same fraction of her take-home pay each month. The total amount of money that she had saved at the end of the year was 3 times the amount of that portion of her monthly take-home pay that she did not save. If all the money that she saved last year was from her take-home pay, what fraction of her take-home pay did she save each month?
~$\frac{1}{2}$~
~$\frac{1}{3}$~
~$\frac{1}{4}$~
~$\frac{1}{5}$~
~$\frac{1}{6}$~
存的总数是每个月没存的三倍,不是存的总是是没存总数的三倍!看清楚题目!
归因:分析错误
是单月未存量的3倍,而非单月未存总量的3倍
“The total amount of money that she had saved at the end of the year was 3 times the amount of that portion of her monthly take-home pay that she did not save.”
年底存钱总数 = 每个月没存的钱的 3 倍
12 * t% * m = 3 * (1-t%) * m
【saved at the end of the year=save each month*12】为什么当时没有反应过来????
12*save each month=3*not save each month
save each month+not save each month=1
Alice去年的收入每月一样,她每月都会存下同样多的钱
年末,她存下的钱,是她每月收入中没存的钱的三倍
她去年省下的所有钱都是来自她的收入,她每月省下了收入的分数?
设月薪y,所求为 X,12*y*X=3*(y—y*X),X=1/5
没注意看到:存钱的总数是一个月没存的钱的三倍~~monthly
每个月存钱为x,没存的部分为y,12x=3y,y=4x
x/(x+y)=1/5
Alice去年的收入每月一样,她每月都会存下同样多的钱
年末,她存下的钱,是她每月收入中没存的钱的三倍
她去年省下的所有钱都是来自她的收入,她每月省下了收入的分数?
12个月总共省的钱 = 3 * 一个月没省的钱.....两边都弄成一个月了....