Pipes A and B can fill a tank in 16 hours and 24 hours, respectively, whereas pipe C can empty the full tank in 40 hours. All three pipes are opened together, but pipe C is closed after 10 hours. After how many hours will the remaining part of the tank be filled?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e 2.
Time taken by Pipe A = 16 hours
Time taken by Pipe B = 24 hours
Time taken by Pipe C = -40 hours [negative sign shows that C emptied the tank]
L.C.M(16, 24, and 40) = 240
The efficiency of Pipe A = 240/16 = 15 units
The efficiency of Pipe B = 240/24 = 10 units
The efficiency of Pipe C = 240/40 = -6 units
When all pipes are opened for 10 hours
Work done = (15 + 10 - 6) × 10 = 19 × 10 = 190 units
Remaining part of the tank = 240 - 190 = 50 units
Time taken by A and B = 50/(15 + 10) = 50/25 = 2 hours