Question

A bucket in the from of a frustum of a cone of height 30 cm with radii of its lower and upper ends as 10 cm and 20 cm, respectively. Find the capacity of the bucket. Also find the cost of milk which can completely fill the bucket at the rate of ₹ 40 per litre. `("Use"  π = 22/7)`

Answer 1

Height of frustum, h = 30 cm,

R₁ = 20 cm and R₂ = 10 cm

Capacity of the bucket

= `1/3 πh [R_1^2 + R_2^2 + R_1R_2]`

= `1/3 xx 22/7 xx 30[(20)^2 + (10)^2 + 20 xx 10]`

= `220/7 [400 + 100 + 200]`

= `220/7 xx 700`

= 22000 cm³

= `22000 xx 1/1000` litre   ...[∵ 1 litre = 1000 cm³]

= 22 litres.

Total cost of milk which can completely fill the bucket = ₹ 40 × 22 = ₹ 880.