GWD-1-26

Ferdinand

Running at their respective constant rates, machine X takes 2 days longer to produce w widgets than machine Y.At these rates, 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

Answer: E

xiongbaobao

假设Machine X生产w widgets需要X天，则Machine Y生产w widgets需要（X-2）天。

根据 two machines together produce 5/4 w widgets in 3 days可以列出等式：
3[w/X+w/(X-2)]=(5/4)w 两边同时约掉w得，3[1/X+1/(X-2)]=5/4可以求出X=6货X=4/5（舍去）
所以Machine X生产w widgets需要6天，因为速率是一定的，所以Machine X生产2w widgets需要12天。
所以选E。

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