Question : Tap A can fill an empty tank in 8 hours if no other tap is open, and tap B can empty the same tank, when filled, in 12 hours, when no other tap is open. Find the time taken to fill the same tank, when empty, if both the taps are opened together.

Question : Three pipes A, B, and C can fill a tank in 6 hours, 9 hours, and 12 hours, respectively. B and C are opened for half an hour, and then pipe A is opened. The time taken by the three pipes together to fill the remaining part of the tank is:

Question : A alone can do $\frac{1}{10}$th part of a work in 8 hours. B alone can do $\frac{1}{5}$th part of the same work in 4 hours. If they work together, then how many hours will they take to complete $\frac{9}{16}$th part of the same work?

Question : Pipe P alone can fill a tank in 18 hours and Pipe Q alone can fill the same tank in 24 hours. If both the pipes are opened on alternate hours one at a time and pipe Q is opened for the first hour, then in how much time the tank will be full?

Question : Pipes P and Q can fill a tank in 12 hours and 36 hours, respectively. If both pipes are opened, then how much time (in hours) will it take to fill the tank?