Pipes A and B can fill a tank in 18 minutes and 27 minutes, respectively. C is an outlet pipe. When A, B, and C are opened together, the empty tank is completely filled in 54 minutes. Pipe C alone can empty the full tank in:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e.13 minutes.
LCM(18, 27, 54) = 54
The efficiency of A = 54/18 = 3 units
The efficiency of B = 54/27 = 2 units
The efficiency of A, B, and C = 54/54 = 1 unit
Efficiency of C = 1 - 5 = - 4 units
Time taken by C = = = minutes