Question

A $20m$ deep well with diameter $7cm$ is dug and the earth from digging is evenly spread out to form a platform $22m$ by $14m$. Find the height of the platform.

Answer 1

Diamter = 7 m

so, radius = 3.5 m

Earth dug out from (cylindrical) well

$=\pi \times r\times r\times h$

$=\frac{22}{7}\times 3.5\times 3.5\times 20$

$=770m^3$

to from platform ...... (cuboidal)

volume of cuboid = $l\times b\times h$

$770=22\times 14\times h$

so, height = $\frac{770}{22}\times 14$$=2.5m$