Question

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

Answer 1

Diameter $=7m$

so, radius $=3.5m$

- earth dug out from (cylindrical) well$=\pi \times r\times r\times h$

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

$=770$

to form platform..... (cuboidal)

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

$770=22\times 14\times h$

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