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 s
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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 s
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Question 1209016: 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? Answer by ikleyn(52754) (Show Source):
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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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The main pump is scheduled to work 3 hours, from 9 am to noon.
In 3 hours, the main pump will make 3/4 of the job;
the remaining 1/4 part of the job should be done by the auxiliary pump.
The auxiliary pump needs = = 2 hours.
Here is the rate of work of the auxiliary tank.
Hence, the auxiliary pump should start 2 hours before noon, i.e. at 9:45 am.
ANSWER. The auxiliary pump should start at 9:45 am.
