GMATPrep T1-Q41-DS

[kaijen]

41. 3690-!-item-!-187;#058&003497
Machines X and Y work at their respective constant rates. How many more hours does it take machine Y, working alone, to fill a production order of a certain size than it takes machine X, working alone?

(1) Machines X and Y, working together, fill a production order of this size in two-thirds the time that machine X, working alone, does.

(2) Machine Y, working alone, fills a production order of this size in twice the time that machine X, working alone, does.

答案是E 我覺得是C耶

機器X獨立完成要X hr 機器Y獨立完成要y hr

聯立方程式
1 / x + 1 / y = 1 / (3分之2*X)
y = 2 x

[Frankts]

同學 根據您列出來的式子
好像沒有辦法算出X和Y
因為第一個式子解出來的=第二個式子