求大牛详解一简单数学题目

pwj8899 · 发表于 2008-7-30 16:34:00

6lice's task-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?

pwj8899 · 发表于 2008-7-30 16:39:00

是　ALICE'S 抱歉

hansomecd · 发表于 2008-7-30 17:01:00

alice一个月赚N元到手（take-home pay）每个月都回存起来一部分M元。到年底了，alice一共存的钱（12个M元），是她每个月花的钱（N-M）的3倍。假设她只有这个经济来源，那么她每个月存的钱占了多少比。

12m=3（n-m）算出m/n就好了

pwj8899 · 发表于 2008-7-30 17:15:00

就说题目么看清原来是每月的3倍还当总共的3倍算了... 谢谢啊

得死命的细心啊...

芒果榴莲 · 发表于 2008-7-30 20:09:00

每月存的占每月收入的比例为F, 每月收入I。则

12 * F * I = 3 * ( 1 - F ) * I

4 * F = 1 - F

F = 1 /5

求大牛详解一简单数学题目