In the bottom of a water tank, there are two drains A and B. If only A is open, it takes 30 minutes to empty a full tank and if only B is open, it takes 20 minutes. If for 10 minutes both drains are open, then B is closed, how much time it takes to empty a full tank?

One tap can fill a water tank in 3 hours and another tap can empty it in 4 hours. If the tank is one-third full and both the taps are opened together, then the time taken to fill the tank will be

A tank is filled by one pipe in 8 hours and emptied by another in 12 hours. Time to fill when both operate?

Three taps A, B and C together can fill a tank in 6 hours. Tap C alone can fill the tank in 12 hours. To fill the tank, when it is empty, all the three taps are started together. After working t hour…

A, B and C are employed to do a piece of work for Rs. 529. A and C are supposed to finish 19/23 of the work together. How much shall be paid to B?

A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is :