Pipes A and B can fill a tank in 7 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 one.
A) 1 13/17 hours	B) 2 8/11 hours	C) 3 9/17 hours	D) 4 8/19 hours	E) None
Solution   Net part filled in 1 hour	= (1/7 + 1/6 -1/12)   = 19/84.   Therefore, the tank will be full in 84/19 hrs.	â€¹=â€º 4 8/19 hrs.   Answer 4 8/19 hours
<result>D</result>
Pipes A and B can fill a tank in 7 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