Confusing DS

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Confusing DS

by [email protected] » Sun Jun 19, 2011 6:09 am
Working together, Michelle and John can type a manuscript in 60 hrs. How long does it take Martha and Jeff working together to type the same manuscript.

Statement 1:
Michelle types 60 wpm and John types 40 wpm.

Statement 2:
Martha types 30 wpm and Jeff types 80 wpm.


According to me the answer is E, but the test answer says that OA is C. Please any of the experts please help....
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by Frankenstein » Sun Jun 19, 2011 6:14 am
Hi,
Let the typing rates of 4 of them be a,b,c,d
From(1): a=60, b=40
a+b = 100wpm
Number of words = 100*(60*60)
No info. about c and
Not sufficient
From(2): c=30, d=80
c+d = 110wpm
No info about number of words
Not sufficient
Both (1) and (2) :
Time taken = 100*60*60/110
Sufficient

Hence, C
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by Geva@EconomistGMAT » Sun Jun 19, 2011 6:28 am
[email protected] wrote:Working together, Michelle and John can type a manuscript in 60 hrs. How long does it take Martha and Jeff working together to type the same manuscript.

Statement 1:
Michelle types 60 wpm and John types 40 wpm.

Statement 2:
Martha types 30 wpm and Jeff types 80 wpm.


According to me the answer is E, but the test answer says that OA is C. Please any of the experts please help....
Since time = work/rate, in order to find the time it takes Martha and Jeff, you need two things:

The amount of work to be done AND
The combined rate of Martha and Jeff

Stat. (1) gives you the work involved: 60 hours * 100*60 wph combined rate.

Stat. (2) gives you the combined rate of Matha and Jake

thus, both are sufficient.

Why did you think that the answer was E?
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