Out of three pipes the first two can fill an empty tank in 9 and 18 hours, respectively while the third can drain the filled tank in 15 hours. If all the three pipes are opened when the tank is empty, after how many hours will the tank be full?

Two pipes, when working one at a time can fill a cistern in 2 hrs and 3 hrs, respectively while a third pipe can drain the cistern empty in 6 hrs. All the three pipes were opened together when the cistern was 1/6 full. How long will it take for the cistern to be completely full?

Pipes A, B and C are attached to an empty cistern. While the first two can fill the cistern in 4 and 10 hrs, respectively, the third can drain the cistern, when filled, in 6 hrs. If all the three pipes are opened simultaneously when the cistern is half-full, how many hours will be needed to fill the cistern?

Two pipes fill a tank when working individually in 25 and 40 hours, respectively while a third pipe can drain the filled tank in 16 hours. If all the three pipes are turned on at the same time when the tank is empty, how long will it take to fill the tank completely ?

One of the two inlet pipes works twice as efficiently as the other. The two, working alongside a drain pipe that can empty a cistern all by itself in 8 hours, can fill the empty cistern in 8 hours. How many hours will the less efficient inlet pipe take to fill the empty cistern by itself?

A pipe can fill a sump with water in 2 hours. Because of a leak, it took 2 2/3 hrs to fill the sump. The leak can drain all the water of the sump in

Two pipes A and B can fill an empty cistern in 18 and 27 hours, respectively. Pipe C can drain the entire cistern in 45 hours when no other pipe is in operation. Initially, when the cistern was empty Pipe A and Pipe C were turned on. After a few Pipe A was turned off and Pipe B was turned on instantly. In all, it took 55 hours to fill the cistern. For how many hours was Pipe B turned on?

Pipes A and C can fill an empty cistern in 32 and 48 hrs, respectively while Pipe B can drain the filled cistern in 24hrs. If the three pipes are turned on together when the cistern is empty, how many hrs will it take for the cistern to be 2/3 full?