Question -
Answer -
Given,
Diameter of thecircular pond = 40 m
So, the radius of thepond = 40/2 = 20 m = r
Thickness (width ofthe path) = 2 m
As the whole view ofthe pond looks like a hollow cylinder.
And the height will be20 cm = 0.2 m
So,
Thickness (t) = R – r
2 = R – 20
R = 22 m
Volume of the hollowcylinder = π (R2– r2) × h
= π (222–202) × 0.2
= 52.8 m3
Therefore, the volumeof the hollow cylinder is the required amount of sand needed to spread acrossto a depth of 20 m.