Question

A well of diameter 4 m dug 21 m deep,The earth taken out of it 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 = πr²h

= π(2)(2)(21)

= 84π

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

⇒ 84π = π(5² − 2²)h

\(h = \frac{84}{25 -4}\)

\(= \frac{84}{21}\)

= 4 m

Answer 2

Diameter of earth dug out = 4 m

Radius of earth dug out = 2 m 

Depth of the earth 21

Height of emb  = 4 m.