Question

How many cube metres of earth must be dug to construct a well $7m$ deep and diameter $2.8m$ ?

Answer 1

The shape of well is considered to be a cylinder.

Given, height $=7m$ and diameter $=2.8m$

Radius $=\frac{\text{diameter}}{2}=\frac{2.8}{2}=1.4m$

Volume of earth dug out = $\pi r^{2}h$ $=\frac{22}{7}\times (1.4{)}^2\times 7$ $=43.12m^3$