Three pipes A, B and C can fill a cistern in 10 hours, 12 hours and 15 hours respectively. First A was opened. After 2 hour, B was opened and after 4 hours from the start of A, C was also opened. Find the time in which the cistern is just full.

Two pipe can fill a cistern in 3 hours and 4 hours respectively and a waste pipe can empty it in 2 hours. If all  the three pipes are kept open, then the cistern will be filled in

A tap takes 36 hours extra to fill a tank due to leakage equivalent to half of its inflow. The inflow can fill the tank in how many hours?

Tank is normally filled in 8 hours but takes 2 hours longer to fill because of a leak in its bottom. If the cistern is full, in how many hours will the leak empty it? 

12 pumps working 6 hours a day can empty a completely filled reservoir in 15 days. How many such pumps working 9 hours a day will empty the same reservoir in 12 days?

A tap can fill a tank in 6 hours. After half the tank is filled, three more similar taps are opened. What is the total time taken to fill the tank completely?

A water reservoir has two inlets and one outlet. Through the inlet it can be filled in 3 hours and 3 hours 45 minutes respectively. It can be emptied completely in 1 hour by the outlet. If the two inlets are opened at 01 : 00 pm and 02 : 00 pm respectively and the outlet at 03 : 00 pm then it will be emptied at : 

The pipe can fill a tank in 36 minutes and the another pipe can empty it in 45 minutes. If both pipes are opened simultaneously, the time (in hours) it takes to fill half the capacity of the tank is: