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:	Options:
A) 3 9 /17 hours  B) 1 13 /17 hours  C) 2 8 /11 hours  D) 4 1 /2 hours  E) None of these
Explanation:   Solution 1   Pipes A and B can fill the tank in 5 and 6 hours respectively. Therefore,   part filled by pipe A in 1 hour =1/5   part filled by pipe B in 1 hour =1/6   Pipe C can empty the tank in 12 hours. Therefore,   part emptied by pipe C in 1 hour =1/12   Net part filled by Pipes A,B,C together in 1 hour =1/5 +1/6+1/12 =17/60   i.e., the tank can be filled in 60/17=3 9/17 hours.   3 9 /17 hoursNSWER IS 3 9 /17 hours
<result>A</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: