Question
Pipes βAβ and βBβ can fill a tank in 6 hours and
9 hours, respectively. If pipe βCβ is opened along with pipes βAβ and βBβ, then the tank gets filled in 9 hours. Find the time taken by pipe βCβ to empty (2/3)th part of the same tank.Solution
Let capacity of the tank = 18 litres (lcm of 6 and 9) Efficiency of pipe βAβ = (18/6) = 3 litres/hour Efficiency of pipe βBβ = (18/9) = 2 litres/hour Efficiency of all the three pipes together = (18/9) = 2 litres/hour Efficiency of pipe βCβ = 2 β (3 + 2) = (-3) litre/hour {Negative sign shows that pipe βCβ is an outlet pipe} Required time taken = {(2/3) Γ 18)}/3 = 4 hours
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