A well of diameter 7 m is dug 20 m deep. The earth taken out is spread evenly over a rectangular plot 70 m long and 22 m wide. By how much does the level of the plot rise? Take $\pi = \frac{22}{7}$.

Explanation

1. 01

   Earth dug out = $\frac{22}{7} \times 3.5 \times 3.5 \times 20 = 770$ m³.

2. 02

   Plot area = $70 \times 22 = 1{,}540$ m².

3. 03

   Rise = $770 \div 1{,}540 = 0.5$ $m = 50$ cm.