Question
Pipe ‘A’ fills a tank in 36 hours and pipe ‘B’
empties it in 90 hours. If both are opened simultaneously, how much time will it take to fill 60% of the tank?Solution
Let the capacity of the tank be 180 litres. So, efficiency of pipe ‘A’ = 180 ÷ A = 5 litres/hour And efficiency of pipe ‘B’ = 180 ÷ B = 2 litres/hour So, combined efficiency of both pipes = 5 – 2 = 3 litres/hour So, time taken to fill 60% of the tank = (180 × 0.60) ÷ 3 = 108 ÷ 3 = 36 hours