Pipes and Cistern


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Pipes & Cisterns


Important points :
1. Inlet Pipe
A pipe which fills up the tank is known as inlet.

2. Outlet Pipe
A pipe which empties the tank is known as outlet.

3. A pipe takes x hours to fill up the tank. Then
x
1
parts of the tank will be filled in 1 hour.

4. A pipe takes y hours to empty the tank. Then part emptied in 1 hour =
y
1


5. Pipe A can fill a tank n times as fast as another pipe B. This means:
i) If slower pipe B takes x min to fill up the empty tank,then faster pipe A takes
n
x
min to fill up the empty tank.

ii) If they operate together, then part of the tank that is filled up in 1 hour is (n + 1)/x

6. Let a pipe can fill a tank in x hours and another pipe can empty the full tank in y hours. We can examine two cases here.
i) x < y
In this case, the net part filled in 1 hour =
x
1
-
y
1

ii) y < x
In this case, the net part emptied in 1 hour =
y
1
-
x
1