Pipes A and B, respectively, can fill a tank in 5 and 6 hours. It may be emptied in 12 hours using Pipe C. The tank will be filled if all three pipes are opened simultaneously:
A. 1 13/17 hours
B.2 8/11hours
C. 3 9/17hours
D. 4 1/2hours
Answer:C
Pipes A and B, respectively, can fill a tank in 5 and 6 hours. It may be emptied in 12 hours using Pipe C. The tank will be filled if all three pipes are opened simultaneously:
A. 1 13/17 hours B.2 8/11hours C. 3 9/17hours D. 4 1/2hours
Explanation: In 1 hour, the net portion was full.1/5 +1/6-1/12= 17/60,In 60/17 hours, or 3 9/17 hours, the tank will be full.