Pipes A and B can fill a tank in 5 hours 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. Choices:	A) 3 9/5	B) 3 9/17	C) 3 7/5	D) 3 7/17	E) None of these
Explanation:   Net part filled in 1 hour =(1/5 + 1/6 - 1/12)   =17/60hrs   =3 9/17   Answer is 3 9/17
<result>B</result>
Pipes A and B can fill a tank in 5 hours 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.