GWD4-13

yuyanhan

请教怎么做GWD4-13

Q13:

Company S produces two kinds of stereos: basic and deluxe. Of the stereos produced by Company S last month, 2/3 were basic and the rest were deluxe. If it takes 7/5 as many hours to produce a deluxe stereo as it does to produce a basic stereo(这句话我弄不明白,犯糊涂), then the number of hours it took to produce the deluxe stereos last month was what fraction of the total number of hours it took to produce all the stereos?

A 7/17

B 14/31

C 7/15

D 17/35

E 1/2

答案是A, 但为何

sammen

Basic=2/3 Deluxe=1/3

D=7/5B

D/all =D/D+B=﹝1/3*7/5B﹞/﹝(1/3*7/5B)+ 2/3﹞

=(7/15)/(17/15)=7/17

founder

以下是引用sammen在2005-5-27 13:29:00的发言： Basic=2/3 Deluxe=1/3 D=7/5B

D/all =D/D+B=﹝1/3*7/5B﹞/﹝(1/3*7/5B)+ 2/3﹞

=(7/15)/(17/15)=7/17

谢谢，我本来还想问这题的解法呢

yuyanhan

原来是这样，我明白了。谢谢