Question

Find the cost of sinking a tube well 280 m deep, having diameter 3 m at the rate of Rs 3.60 per cubic metre. Find also the cost of cementing its inner curved surface at Rs 2.50 per square metre.

Answer 1

We have,

Depth of tube well = 280 m

Diameter of tube well = 3 m

Radius of well = d/2 = 3/2 = 1.5 m

Volume = πr²h

= 22/7 × 1.5 × 1.5 × 280

= 1980 m³

∴ Cost of sinking tube well at rate Rs 3.60/m³ = 1980 × 3.60 = Rs 7128

Curved surface area = 2πrh

= 2 × 22/7 × 1.5 × 280

= 2640 m²

∴ Cost of cementing its inner curved surface at rate Rs 2.50/m² = 2.50 × 2640 = Rs 6600