PIPES AND CISTERNS – SOLVED EXAMPLES

In our earlier post we have already discussed PIPES AND CISTERNS SHORTCUTS. Before proceeding to this post, we suggest you to first go through the same.



Example 1: Pipes ‘A’ and ‘B’ can fill a tank in 10 hours and 15 hours respectively. If both pipes are opened simultaneously, how much time will be taken to fill the tank?
  Solution: The required time (See Rule-2)
Example 2: A tap can fill the cistern in 8 hrs. and another can empty it in 16 hrs. If both the taps are opened simultaneously, how much time will be taken to fill the tank?
Solution: The required time (See Rule-1)
Example 3: A pipe can fill a tank in 15 hrs. Due to a leak in the bottom it is filled in 20 hrs. If the tank is full, how much time will the leak take to empty it?
Solution: The required time (it will be solved in the same way as we solved example 2)
Example 4: Pipe A can fill a tank in 20 hours while pipe B alone can fill it in 30 hours and pipe C can empty the full tank in 40 hours. If all the pipes are opened together, how much time will be needed to make the tank full?
Solution: The required time
Example 5: There is a leak in the bottom of a cistern. When the cistern is thoroughly repaired, it would be filled in 3.5 hrs. It now takes half an hour longer. If the cistern is full, how long would the leak take to empty the cistern?
Solution: The required time
Example 6: A tank has a leak which would empty it in 8 hrs. A tap is turned on which admits 6 liters a minute in to the tank, and it is now emptied in 12 hrs. How many liters does the tank hold?
Solution: The time taken to fill the tank
Capacity of tank =24 * 60 * 6 = 8640 liters.
Example 7: A tank is normally filled in 8 hrs. but takes 2 hrs.longer to fill because of leak in its bottom. If the cistern is full, in how many hours will the leak empty it?
Solution: When leak doesn’t work the tank is filled in 8 hrs.
When both filler pipe and leak work together, the tank is filled in 8+2 = 10 hrs.
Therefore, the time taken by leak to empty the tank

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PIPES AND CISTERNS – SOLVED EXAMPLES