Four pipes can fill a reservoir in 15, 20, 30 and 60 hours respectively. The first one was opened at 6 AM, second at 7 AM, third at 8 AM and the fourth at 9 AM. When will the reservoir be filled?

Similarly, the second, third and fourth pipes fill

1

,

1

and

1

of reservoir in one hour respectively.

20

30

60

Let 't' be the number of hours spent by first pipe. The second pipe opened at 7 AM, i.e. one hour later, therefore it worked (t − 1) hours. Similarly, the third and fourth pipes worked (t − 2) and (t − 3) hours respectively. Together all pipes fill the whole reservoir, so we obtain the following equation:

A pipe can fill a tank in 24 hrs. Due to a leakage in the bottom, it is filled in 36 hrs. if the tank is half full, how much time will the leak take to empty the tank?

There are two taps A and B to fill up a water tank. The tank can be filled in 40 min, if both taps are on. The same tank can be filled in 60 min, if tap A alone is on. How much time will tap B alone take, to fill up the same 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 hour and if pipe A is opened first then in how many hours, the tank shall be full?