1)

A tap can fill a tank in 6 hours. When the tank is half filled, three more similar taps are opened to fill water into the same tank. What is the total time taken to fill the tank completely by all the four pipes?

2)

Three pipes A, B and C can fill a tank in 6 hours. After three pipes worked for 2 hours C is closed. Then A and B filled the remaining part in 7 hours. calculate the number of hours taken by C alone to fill the tank is?

3)

A tank can be filled by a pipe A in 2 h and pipe B in 6 h. At 10 am pipe A was opened. At what time will the tank be filled if pipe B is opened at 11 am?

**[SSC CGL 2012]**

4)

Two pipes A and B can separately fill a cistern in 60 min and 75 min respectively. There is a third pipe in the bottom of the cistern to empty it. If all the three pipes are simultaneously opened, then the cistern is full in 50 min. In how much time the third pipe alone can empty the cistern?

**[CAT level]**

5)

A pump can fill a tank with water in 2 h. Because of a leak in the tank, it takes $2\frac{1}{3}$ h to fill the tank. The leak can empty the filled tank in___

**[SSC CPO 2006, CGL 2002]**

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