Two pipes A and B can fill a tank in 12 hours and 18 hours, respectively. Both pipes are opened simultaneously. In how much time will the empty tank be filled completely?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e 7 hours 12 minutes.
Time taken by Pipe A = 12 hours
Time taken by Pipe B = 18 hours
L.C.M = (12 and 18) = 72 units
The efficiency of Pipe A = 72/12 = 6 units
The efficiency of Pipe B = 72/18 = 4 units
Time taken to fill the tank = 72/(6 + 4) = 72/10 = 7 hours and 12 minutes