一道prep关于比例的数学题，求解

norris1938 · 发表于 2016-7-18 07:53:04

Last year, sales at Company X were 10% greater in February than in January, 15% less in March than in February, 20% greater in April than in March, 10% less in May than in April, and 5% greater in June than in May. On which month were sales closes to the sales in January?

请问NN有没有什么好的解题方法？可以在考场上用的方法

ccp92 · 发表于 2016-7-18 09:45:15

你先设一个起始数，比如一月的sales是x，然后其他月的sales都可以算啦

CaesarMBA · 发表于 2016-7-18 10:54:53

On which month were sales closes to the sales in January? --> Assume the sales in Jan. is “a”

10% greater in February than in January, --> Sales in Feb. is 1.1a
15% less in March than in February, --> Sales in Mar is 1.1a * 0.85
20% greater in April than in March, --> Sales in Apr is 1.1a * 0.85 *1.2
10% less in May than in April, --> Sales in May is 1.1a * 0.85 *1.2 * 0.9
and 5% greater in June than in May. --> Sales in Jun is 1.1a * 0.85 *1.2 * 0.9 *1.05

假设a = 100 (为什么呢? 因为比较好算而已)

Jan = 100
Feb = 110
Mar = 93.5
Apr=112.2
May=100.98
Jun=106.029

明显得知: May较接近Jan
(考场上: 假设Jan, 接下来每个月都可以利用上个月求出的数值再乘以一个倍数)

norris1938 · 发表于 2016-7-18 22:50:14

我也是用这种方法算的。有没有更简洁一点的方法算？估计手算，算到May 差不多就晕了。。。

一道prep关于比例的数学题，求解

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