Freshers India

To fill a cistern, pipes A, B and C take 20 minutes, 15 minutes and 12 minutes respectively. The time in minutes that the three pipes together will take to fill the cistern, is : . [Assistant Grade]                        

Two pipes A and B together can fill a cistern in 4 hours. Had they been opened separately, then B would have taken 6 hours more than A to fill the cistern. How much time will be taken by A to fill the cistern separately?                        

A cistern has two taps which fill it in 12 mm. and 15 mm. respectively. There is also a waste pipe in the cistern. When all the three are opened, the empty cistern is full in 20 minutes. How long will the waste pipe take to empty the full cistern ?                        

A cistern can be filled by pipe A and B in 25 hours and 30 hours respectively. There is also an outlet C which can empty it in 40 hours. If all the taps are open together. After 5 minutes pipe C must be turned off. In how much time the cistern is full?                         

A tank has a leak which would empty it in 16 hours. A tap is turned on which admits 12 liter a minute into the tank and it is now emptied in 24 hours. How many liters does the tank hold?                        

A leak in the bottom of a tank can empty the full tank in 8 hours. An inlet pipe fills water at the rate of 6 litres a minute. When the tank is full, the inlet is opened and due to the leak, the tank is empty in 12 hours. How many litres does the cistern hod?