[" 7.Pipes "A" and "B" can fill a tank in "20" hours and "],[30" hours respectively and pipe "C" can empty "],[" the full tank in "40" hours.If all the pipes are "],[" opened together,how much time will be needed "],[" to make the tank full? "]

Pipes A and B can fill a tank in 20 hours and 30 hours respectively and pipe C can empty the full tank in 40 all the pipes are opened together, how 4oc-lii much time will he needed to make the tank full? 10 3/7hou r s b. 12 4/5hou r s c. 17 1/7hou r s d. 19 1/4hou r s

Pipes A and B can fill an empty tank in 6 and 8 hours respectively, while pipe C can empty the full tank in 10 hours. If all three pipes are opened together, then the tank will get filled in:

Pipe A can fill a tank in 30 min , while pipe B can fill the same tank in 10 min and pipe C can empty the full tank in 40 min. If all the pipes are opened together, how much time will be needed to make the tank full?

Two pipes A and B can alone fill a tank in 6 hours and 9 hours respectively. Pipe C can alone empty the same tank in 6 hours. If all three pipes are opened together, then in how many hours will the tank be filled?

Pipe A can fill a tank in 6 hrs while pipe B alone can fill it in 5 hrs and pipe C can empty the full tank in 8 hrs. If all the pipes are opened together, how much time will be needed to completely fill the tank?

Pipe A can fill a tank in 20 h while pipe B alone can fill it in 10 h and pipe C can empty the full tank in 30 h . If all the pipes are open together , how much time will be needed to make the tank full ?