Water is flowing at the rate of 3km/hr through a circular pipe of 20cm internal diameter into a circular cistern of diameter 10m and depth 2m.  In how much time will the cistern be filled?

Explanation

To solve the problem step by step, we will calculate the volume of the cistern, the flow rate of water through the pipe, and then determine the time required to fill the cistern.

### Step 1: Calculate the Volume of the Cistern
The cistern is in the shape of a cylinder. The formula for the volume \( V \) of a cylinder is given by:

\[ V = \pi r^2 h \]
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