Pipes A and B can fill a tank in 5 and 6 hours respectively. Pipe C can empty it in 12 hours. If all the three pipes are opened together, then the tank will be filled in Choose the correct choice from the following options:
A) 1×13/17 hours
B) 2×8/11 hours
C) 3×9/17 hours
D) 4×1/2 hours
E) None
Solution   Net part filled in 1 hour	= (1/5 + 1/6 -1/12)   = 17/60.   Therefore, the tank will be full in 60/17 hrs.	‹=› 3×9/17 hrs.   Answer 3×9/17 hours
<result>C</result>
Pipes A and B can fill a tank in 5 and 6 hours respectively. Pipe C can empty it in 12 hours. If all the three pipes are opened together, then the tank will be filled in