# Two pipes A and B can separately fill a cistern in 60 and 75 mins respectively, there is a third pipe in the bottom...

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Two pipes A and B can separately fill a cistern in 60 minutes and 75 minutes respectively. There is a third pipe in the bottom of the cistern to empty it. If all the three pipes are simultaneously opened, then then the cistern is full in 50 minutes. In how much time the third pipe alone can empty the cistern?

posted May 16, 2018

100 minutes

If the cistern volume is 1, then in one min flow through pipes will be: A- 1/60, B- 1/75, C (third pipe)- 1/x
50*1/60+50*1/75=50*1/x+1
and we find x=100,

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