Three pipes A , B and C takes 15, 24 and 36 minutes respectively to fill a tank. Pipe D can empty it in 1 hour. If all the four pipes are kept open then find the time taken to fill the tank. 

Pipe A can fill a tank in 4 hours and pipe B can fill it in 6 hours. If they are opened on alternate hours and if pipe A is opened first then in how many hours, the tank shall be full? 

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:

A tap can fill the tank in 8 hours and another can empty it in 16 hours. If both the taps are opened simultaneously, the time (in hours) to fill the tank is__.

Two pipes P and Q can fill a cistern in 36 and 48 minutes respectively. Both pipes are opened together, after how many minutes should Q be turned off,so that the cistern be fill in 24 minutes?

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? 

Pipe A can fill a tank in 6 hours. Pipe B can fill the same tank in 10 hours – pipe A, B, C together can fill the same tank in 12 hours. In how many hours pipe C can fill the tank alone?

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.