Working rate question

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Working rate question

by josephcho77 » Thu Oct 18, 2007 6:44 am
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


Can anyone please help me to solve this problem? Thanks!

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by arocks » Thu Oct 18, 2007 8:27 am
Another approach -

two machines together produce 5/4 w widgets in 3 days
or 5w in 12 days or 1w in 2.4 days.
So, x and y's one day's work = 1/2.4

If you look at the qu. and plug-in the values - lets say, it takes x 6 days to produce w, so it will take y 4 days.

X takes 2 days longer to produce w widgets than machine Y (given)

x's one day's work = 1/6; y's one day's work = 1/4
1/6+1/4 = 1/2.4

x takes 6 days to complete 1w or 12 days to complete 2w

Ans: E