Question

One tap can fill a cistern in 2 hours and another can empty the cistern in 3 hours

Answer 1

Your question: One tap can fill a cistern in 2 hours and another empty the cistern in 3 hours.How long will they take to fill the cistern if both the taps are opened ?

Solution: Add the rate of filling and

subtract the rate of emptying

( 1 cistern filled / 2 hrs ) minus ( 1 cistern emptied / 3 hrs ) = ( 1 cistern filled / t hrs )

+1%2F2+-+1%2F3+=+1%2Ft+

Multiply both sides by +6t+

+3t+-+2t+=+6+

+t+=+6+

It will take 6 hrs with both taps open