A pipe can fill a tank in x hours and an another can empty it in y hours. In how many hours will they together fill it. If y>x?

Two pipe A and B can fill a tank in 16 hrs and 12 hrs respectively. The capacity of the tank is 240 litres. Both the pipes are opened simultaneously and closed after 2 hrs. How much more water (In Liters) needed to fill the tank?

A tank can be filled with water by two pipes A and B together in 36 minutes. If the pipe B was closed after 30 minutes, the tank is filled in 40 minutes. The pipe B can alone fill the tank in?

Two pipes P and Q would fill a cistern in 24 hours and 32 hours respectively. If both pipes are opened together, find when the pipe “P” must be turned off so that the cistern may be just filled in 16 hours-

Water flows into a tank which is 200 m long and 150 m wide, through a pipe of cross-section (0.3m x 0.2m) at 20 km/h. In what time will the water level be 8 m?