Question
Pipe βAβ can fill a tank in 30 hours while pipe
βBβ can empty it in 40 hours. They were operated on alternate hours starting with pipe βAβ. Find the percentage of tank filled this way in 60 hours.Solution
Let the total capacity of tank be 120 units Efficiency of pipe βAβ = 120/30 = 4 units/hour Efficiency of pipe βBβ = 120/40 = 3 units/hour Tank filled in 2 hours = (4 β 3) = 1 units Therefore, tank filled in (2 Γ 30 = 60 hours) = 1 Γ 30 = 30 units Required percentage of tank filled = (30/120) Γ 100 = 25%
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