One-fourth of a tank holds135 litres of water. What part of the tank is full if contains 180 litres of water?

A tank can be filled by A in 60 minutes and emptied by B in 75 minutes. The tank is half filled and Ravi wants to fill the tank but opens B mistakenly and realizes after half hour and closed tap B. He then opens A and tank is completely filled in _______ minutes.

Pipes A and B can fill a tank in 12 minutes and 15 minutes, respectively. The tank when full can be emptied by pipe C in x minutes. When all the three pipes are opened simultaneously, the tank is full in 10 minutes. The value of x is:

Pipes A and B can fill a tank in 43.2 minutes and 108 minutes, respectively. Pipe C can empty it at 3 litres/minute. When all the three pipes are opened together, they fill the tank in 54 minutes. The capacity (in litres) of the tank is:

There are two inlets A and B connected to a tank. A and B can fill the tank in 32 h and 28 h, respectively. If both the pipes are opened alternately for 1 h, starting with A, then in how much time (in hours, to nearest integer) will the tank be filled? 

There are three taps of diameter 2 cm, 3 cm and 4 cm, respectively. The ratio of the water flowing through them is equal to the ratio of the square of their diameters. The biggest tap can fill an empty tank alone in 81 min. If all the taps are opened simultaneously, then how long will the tank take (in min) to be filled?

Two pipes, D and E, can fill a cistern in 26 and 78 hours, respectively, while working alone. If the two pipes are opened together, the time taken to fill the cistern is:

A pipe can empty a tank in 40 minutes. A second pipe with diameter twice as much as that of the first is also attached with the tank to empty it . The two pipe together can empty the tank in: