SOLUTION: An old machine can do a certain unit of work in 12 hours. To increase production, a more modern machine is put into operation. And both machines now take 4 hours to do the work. If
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Question 825961: An old machine can do a certain unit of work in 12 hours. To increase production, a more modern machine is put into operation. And both machines now take 4 hours to do the work. If the old machine breaks down, how long will it take the new machine to do the work alone? Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website! Old machine's rate of working is:
( 1 unit of work ) / ( 12 hrs )
Rate of working with both machines:
( 1 unit of work ) / ( 4 hrs )
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Let the rate of the new machine be:
( 1 unit of work ) / ( t hrs )
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Add their rates of working to get their
rate of working together:
Multiply both sides by
The new machine takes 6 hrs to do the work alone
check:
OK
