self Maths Puzzle

There are 12 pipes that are connected to a tank. Some of them are fill pipes and the others are drain pipes. Each of the fill pipes can fill the tank in 8 hours and each of the drain pipes can drain the tank completely in 6 hours. If all the fill pipes and drain pipes are kept open, an empty tank gets filled in 24 hours. How many of the 12 pipes are fill pipes?

Read Solution (Total 1)

ans-48/7 days

explanation: 1 pipe fill in 8 hours and other empty in 6 hours so efficiency of filling water is 3 and efficiency of draining water is 4
so total work= efficiency * time
if efficiency of one filling pipe is 3 then for n filling pipe is 3n
Similarly efficiency of draining pipe is 4(12-n)
total time for filling water= total work/total efficiency
24 = 24/(3n - 4(12-n))
n=48/7
11 years agoHelpfull: Yes(0) No(1)

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