2 jijing questions

brigittew

54.一东东的价格为p，先下降了x percent(注意是x%,不是x),后下降2x percent,问最后价格，用p表示：
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P*(100-x)(100-2x)/10000

why not p(1-x)(1-2x), since here the question is to get the final price, and x here express the percentage?

24. 此题是我数学的最后一道,花了我最后5分钟.实在是理解有问题,最后选的答案竟然和我自己的答案还是不一样,请大家讨论吧.这到数学怎么和阅读有一拼.
From the beginning of last year, Price per share increased K percent. Earning per share increased M percent. Question: ask the ratio in percentage for price per share to earning per share in increase. In term of K, M.
[确认](K-M)/(100+M)。此题是一老JJ

i calculated it for near half an hour, however i cant get any expression like the above, can anyone tell me the detailed method used here?

thanks in advance

skycrash

24. the easy way.
suppose the original price is 100.so after increase,
price per share is 100(1+k/100)=100+k
earning per share is 100(1+M/100)=100+m
so the result is (100+k-100-m)/(100+m)=(k-m)/(100+m)
half an hour, sorry, I think you make a spelling mistake, half a min, right?

tongxun

bigittew:
54、题目已经说明了X 是剔除了百分比后的数字，比如75%，X=75，所以是100-75，而不是1-75
24、[x(1+k%)/y(1+m%) - x/y]/(x/y)

skycrash

why not make life easy. don't need always use the standard way.

tongxun

同意！以后我就用你的方法！谢谢。

brigittew

i see, thanks so much!!