Question

A well of diameter 4 m is dug 21 m deep. The earth taken out of its has been spread evenly all around it in the shape of a circular ring of width 3 m to form an embankment. Find the height of the embankment.

Answer 1

Given, Diameter $=4$ m

Radius $=2$ m $h=21$ m

$V=\pi r^{2}h=\pi \left(2\right)\left(2\right)\left(21\right)=84\pi$

Volume of soil dug from well = volume of earth used to form embankment

$\Rightarrow 84\pi =\pi (5^2-2^2)h$

$h=\frac{84}{25-4}=\frac{84}{21}=4m$