Question

Question 89

How many cubic meters of Earth must be dug to construct a well 7 m deep and of diameter 2.8 m?

Answer 1

A well is in the form of cylindrical form.

Earth dug to construct a well 7 m deep and diameter 2.8 m should be equal to the volume of a cylinder with 7 m height and diameter 2.8 m.

Volume of a cylinder
$=\pi r^{2}h$
$=\frac{22}{7}\times \frac{2.8}{2}\times \frac{2.8}{2}\times 7$
$=11\times 2.8\times 1.4$
$=43.12m^3$

Therefore, 43.12 cubic metres of Earth needs to be dug out to construct the required well.