Two pipes can fill a tank in 10 hours and 12 hours respectively, while a third pipe empties the full tank in 20 hours. If all the three pipes operate simultaneously, in how much time will the tank be full?

Question

Philoid · Accepted Answer

Number of hours inlet A requires to fill the cistern : 10 hours

Number of hours inlet B requires to fill the cistern : 12 hours

Number of hours outlet C requires to empty the cistern : 20 hours

Part of the cistern filled by inlet A in one hour:

Part of the cistern filled by inlet B in one hour:

Part of the cistern emptied by outlet C in one hour:

Work done by pipes A, B and C together in one hour: + – = =

They can fill the cistern together in hours = 7 hrs 30 min