SOLUTION: An oil tanker can be emptied by the main pump in 4 hours. An auxiliary pump can empty the tanker in 9 hours. If the main pump is started at 9 am, when should the auxiliary pump be
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-> SOLUTION: An oil tanker can be emptied by the main pump in 4 hours. An auxiliary pump can empty the tanker in 9 hours. If the main pump is started at 9 am, when should the auxiliary pump be
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Question 413168: An oil tanker can be emptied by the main pump in 4 hours. An auxiliary pump can empty the tanker in 9 hours. If the main pump is started at 9 am, when should the auxiliary pump be started so that the tanker is emptied by noon?
You can put this solution on YOUR website! An oil tanker can be emptied by the main pump in 4 hours. An auxiliary pump can empty the tanker in 9 hours. If the main pump is started at 9 am, when should the auxiliary pump be started so that the tanker is emptied by noon?
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hourly work rate of main pump=1/4
hourly work rate of aux pump=1/9
Let x=no of hours auxiliary pump needed to be working to finish the job by noon.
no of hours main pump would have worked if started at 9AM and finished by noon=3
..
(1/4)*3+(1/9)*x=1
3/4+x/9=1
x/9=1-3/4
x/9=1/4
x=9/4=2+1/4 hours
ans:
The auxiliary pump must be stated 2+1/4 hours before noon or at 9:45AM
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