Question
Pipe βAβ can fill a tank in 30 hours whereas leak
βAβ can empty it in 45 hours. If they both operate along with pipe βBβ, then the given tank gets filled in 20 hours. How much time is needed to fill the given tank if pipe βBβ and leak βAβ work together?Β ΒSolution
Let the capacity of the tank be 90 litres {LCM (30 and 45)} Efficiency of pipe βAβ = 90 Γ· 30 = 3 litres/hour Efficiency of leak βAβ = 90 Γ· 45 = 2 litres/hour Combined efficiency of pipe βAβ and leak βAβ = 3 β 2 = 1 litre/hour Combined efficiency of pipe βAβ, βBβ and leak βAβ = 90 Γ· 20 = 4.5 units/hour Efficiency of pipe βBβ = 4.5 β 1 = 3.5 units/hour Time taken by pipe βBβ and leak βAβ to fill the tank = 90 Γ· (3.5 β 2) = 60 hours
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