※ 引述《oranger (从新出发)》之铭言： : GWD3-18 : Last year the price per share of Stock X increased by k percent and the : earnings per share of Stock X increased by m percent, where k is greater : than m. By what percent did the ratio of price per share to earnings per : share increase, in terms of k and m ? : Ans: [100(k-m)]/(100+m)% : GWD5-28 : 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 : Newapaper A and if p percent of the newspapers that the store sold were copies : of Newspaper A, which of the following expresses r in terms of p ? : Ans: 400p/(500-p) : 请帮忙解答一下,谢谢!! 回答一下 GWD 5-28 设 newspaper A 卖 A分 newspaper B 卖 B分 方程式1. (A+1.25B)r=A ==> A=1.25Br/(1-r) 代入方程式2 方程式2 (A+B)p= B ==> 1.25pBr/(1-r) + BP = 1.25Br/(1-r) ==> 消B & 通乘 (1-r) ==> 1.25pr + p-pr= 1.25r ==> 移项 r(1.25-1.25p+p)=p ==> r= p/ (1.25-0.25p) 这边我也有问题 通乘 400後得 r=400p/(500-100p) 不过我还是挑了这个答案 因为 没得选 orz 拜托大家看看哪边有错罗 --

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