Two pipes A and B can fill a tank in 12 minutes and 15 minutes, respectively. When an outlet pipe C is also opened, then the three pipes together can fill the tank in 10 minutes. In how many minutes can C alone empty the full tank?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 20.
Time taken for Pipe A to fill the tank = 12 minutes
Part of a tank filled by Pipe A in an hour = 1/12
Time taken for Pipe B to fill the tank = 15 minutes
Part of a tank filled by Pipe B in an hour = 1/15
Time taken for Pipe C to empty the tank = x minutes
Part of tank emptied by Pipe C in an hour = 1/x
ATQ -
(1/12) + (1/15) - (1/x) = (1/10)
(1/x) = (1/12) + (1/15) - (1/10)
(1/x) = (5 + 4 - 6)/60
(1/x) = 3/60
x = 20 minutes