Two inlet pipes A and B can fill an empty cistern in 35 hours and 52.5 hours respectively while Pipe C is an outlet pipe that can drain the filled cistern in 17.5 hours. When the cistern is full Pipe C is left open for an hour, then closed and Pipe A is opened for an hour, closed and Pipe B is opened for an hour. The process continues till the cistern is empty. How many hours will it take for the filled cistern to be emptied?

Two inlet pipes A and B can fill an empty cistern in 35 hours and 52.5

1.	Two inlet pipes A and B can fill an empty cistern in 35 hours and 52.5 hours respectively while Pipe C is an outlet pipe that can drain the filled cistern in 17.5 hours. When the cistern is full Pipe C is left open for an hour, then closed and Pipe A is opened for an hour, closed and Pipe B is opened for an hour. The process continues till the cistern is empty. How many hours will it take for the filled cistern to be emptied?
A.	301
B.	313
C.	298
D.	315
Answer» D. 315