Question

A 14 m deep well with inner diameter 10 m is dug and the earth taken out is evenly spread all around the well to form an embankment of width 5 m. Find the height of the embankment.

Answer 1

Inner diameter = 10 m

Inner radius = 5 m

Inner height = 14 m

Volume of the cylinder = πr² h cubic units

= \(\frac{22}{7}\) x 5 x 5 x 14

= 1100 m³

Volume of the hollow = n(R² – r²)h cubic units

R = 10 m

r = 5 m

= \(\frac{22}{7}\) x (10² - 5²)h = 1100 m³

(∵ the earth taken out = the earth spread all around)