求解一道GWD数学~谢谢大家~

zhangtysun

Last Sunday a certain store sold copies of Newspaper A for $1.00 each and copies of Newspaper B for $1.25 each, and the store sold no other newspapers that day.If r percent of the store’s revenues from newspaper sales was from Newspaper A and if p percent of the newspapers that the store sold were copies of newspaper B, which of the following expresses r in terms of p?



A.100p / (125 – p)

B.150p / (250 – p)

C.300p / (375 – p)

D.400p / (500 – p)

E.500p / (625 – p)

白菜白菜

这题似乎以前讨论过，是有问题的，这里都说了no other newspapers that day.  那r+p肯定=1吖
那r=1-p呀，题目不对的

lele411

4-4p/ p+4   我咋算出这个来了？没有答案啊

sxkiller007

看清题目，r是 关于revenue的  p 是销售数量

zhangtysun

有人说是设总量为100 A的数量就是p 这个我就没理解~ 我觉得A的数量应该是r才对~

zhangtysun

有没有大神帮我解答啊` x偶已经要崩溃了~

白菜白菜

看错了~=。=这题没错，设A、B报纸非别卖了A、B份，则有r/100=A/(A+1.25B)   p/100=B/(A+B)
由后一个式子可以得出A=（100-P)B/p  代入第一个式子，化简出来，比较复杂，但B可以消掉，答案就是D。。

zhangtysun

我化简到r=100（100-p）/100-0.25p 就化简不下去了~

白菜白菜

其实还好啊~慢慢化简 这个还不是很烦的 是不是哪里出错了=。=

ClaudiaJL

我化简到r=100（100-p）/100-0.25p 就化简不下去了~

-- by 会员 zhangtysun (2012/9/10 16:01:38)

不要忧伤 我来救你？？！！！
正确题目如下：
Last Sunday a certain store sold copies of Newspaper Afor $1.00 each and copies of Newspaper B for $1.25 each, and the store sold no other newspapers that day.  If r percent of the store’s revenues from newspaper sales was from Newspaper A
and if p percent of the newspapers that the store sold were copies ofnewspaper A, which of the followingexpresses r in terms of p?
A.   100p / (125 – p)
B.    150p / (250 – p)
C.    300p / (375 – p)
D.    400p / (500 – p)
E.    500p / (625 – p)
你列式子无问题，此楼题目稍不对。