  # A cistern has three pipes A, B and C. The pipes A and B can fill it in 4 and 5 hours respectively...

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A cistern has three pipes A, B and C. The pipes A and B can fill it in 4 and 5 hours respectively and C can empty it in 2 hours. If the pipes are opened in order at 1, 2 and 3 am respectively..
When will the cistern be empty? posted Apr 29, 2016

the cistern will be empty at 5pm.
because by pipe a, b ,filled part of cistern respectively 1/4, 1/5 in 1 hour, and pipe b khali krega 1/2part of cistern,
so at 5 pm full work done by three pipes=
16/4+15/5-14/2=0. answer Apr 30, 2016

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