Question 355113
inlet pump fills in 10 hours
so it does 1/10 of the job in 1 hour.
outlet pump takes 30 hours
so it can do 1/30 of the job in 1 hour.
..
when both  are open they will do 1/10 -1/30 of the job in 1 hour
=2/30 = 1/15 of the job in one hour.
so the tank will fill in 15 hours when both are on.
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m.ananth@hotmail.ca