Question
Pipes A and B can fill a tank in 43.2 minutes and 108
minutes, respectively. Pipe C can empty it at 3 litres/minute. When all the three pipes are opened together, they fill the tank in 54 minutes. The capacity (in litres) of the tank is:Solution
LCM of 43.2, 108 and 54 = 432 units = Total work Efficiency of A = 432/43.2 = 10 units/min Efficiency of B = 432/108 = 4 units/min Efficiency of (A + B + C) = 432/54 = 8 units/min Efficiency of C = (10 + 4 – 8) units/min ⇒ 6 units/min Capacity of tank = (432/6) × 3 litres ⇒ (72 × 3) litres ⇒ 216 litres
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