gmatprep - work/rate

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by Ian Stewart » Sat Sep 18, 2010 6:20 pm
The first machine processes 100 units in 5 hours, so processes 20 units per hour, or 40 units in 2 hours. Since we want to process a total of 100 units in 2 hours, the other machine will need to process 60 units in 2 hours, or 30 units per hour.
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by klmehta03 » Sat Sep 18, 2010 7:50 pm
Assume the rate for new machine is x units/ hr
as revised combined rate for two machines (old and new) is 50 machines/hr
and rate for the old machine is 20 units/hr
20 + x= 50
x= 30 units/hr

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by Gurpinder » Sat Sep 18, 2010 10:02 pm
Ian Stewart wrote:The first machine processes 100 units in 5 hours, so processes 20 units per hour, or 40 units in 2 hours. Since we want to process a total of 100 units in 2 hours, the other machine will need to process 60 units in 2 hours, or 30 units per hour.
That was easy!!!

Thx!
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