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标题: 天山6-26 怎么不会算了? [打印本页]

作者: renprince    时间: 2005-8-29 06:14     标题: 天山6-26 怎么不会算了?

Q26

Running at their respective constant rates, machine X takes 2 days longer to produce W widgets than machine Y. At these rate, if the two machines together produce 5/4 W widgets in 3 days, how many days would it take machine X alone to produce 2W widgets?

A.4

B.6

C.8

D.10

E.12

答案是E, 可是我算了半天都是C。 谁能告诉我答案是怎么算出来的,谢谢!


作者: luoye1    时间: 2005-8-29 16:10

这题我也算错了
作者: assfgrtrtr    时间: 2005-8-29 20:37

(5/4)/(1/x+1/(x+2))=3==>x=6,x=5/4

2/(1/6)=12

设Xmachine X天完成,Ymachine X+2天完成,效率分别是1/x,1/x+2


作者: xiongxiong88    时间: 2005-8-31 06:04

楼主强,顶一下!!




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