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? Answers
A) 3	B) 3 9/11	C) 3 9/17	D) 4	E) 4 1/7
Net part filled in 1 hour 1	+	1	-	1 =	17	.   5	6	12	60   The tank will be full in	60/17	hours i.e., 3 9/17	hours.   3 9/17)
<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?