Pipes A and B can fill a tank in 8 hours and 12 hours, respectively whereas pipe C can empty the full tank in 6 hours. A and B are opened for 3 hours and then closed and C is opened instantly. C will empty the tank in:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 15/4 hours
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Understanding |
Application |
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Since pipe A and B can fill the tank alone in 8 and 12 hours respectively and pipe C can empty it in 6 hours alone. Total capacity of tank = LCM of 8, 12 and 6 = 48 units Efficiency of A = 48/8 = 6 Efficiency of B = 48/12 = 4 Efficiency of C = 48/6 = 8
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A and B are operated by 3 hours: Units filled = (6 + 4) × 3 = 30 units After that C is opened: Time taken by C to empty the tank = (30/8) hours = 15/4 hours |