Surface Areas and Volumes — Question 7

Given,

Diameter of the conical pit (d) = 3.5 m

Radius of the conical pit (r) = $\dfrac{\text{Diameter}}{2} = \dfrac{3.5}{2}$ = 1.75 m

Depth of the conical pit (h) = 12 m

By formula,

Volume of conical pit (V) = $\dfrac{1}{3}πr^2h$

Substituting values we get :

$V = \dfrac{1}{3} \times \dfrac{22}{7} \times (1.75) ^2 \times 12 \\[1em] = \dfrac{1}{3} \times \dfrac{22}{7} \times 3.0625 \times 12 \\[1em] = 22 \times 0.4375 \times 4 \\[1em] = 38.5 \text{ m}^3.$

As,

1 m³ = 1000 Litres = 1 kilo litres

38.5 m³ = 38.5 × 1 kilo litres = 38.5 kl.

Hence, the capacity of the conical pit is 38.5 kilo litres.