Find the cost of sinking a tubewell 280 m deep, having diameter 3 m at

1.	Find the cost of sinking a tubewell 280 m deep, having diameter 3 m at the rate of Rs. 3.60 per cubic meter. Find also the cost of cementing its inner curved surface at Rs. 2.50 per square meter.
Answer» Given, Depth of tubewell = 280 m Diameter of tubewell = 3 m So radius = \(\cfrac32\) m Volume of tubewell = πr²h = \(\cfrac{22}7\times\cfrac94\times\)280 = 1980 m³ Curved surface area of tubewell = 2πrh = 2\(\times\cfrac{22}7\times\cfrac{3}2\times\)280 = 2640 m² ∴ cost of sinking at rate Rs 3.60/m³ = 3.60 × 1980 = Rs. 7128. ∴ cost of cementing at rate Rs. 2.50/m² = 2.50 × 2640 = Rs. 6600.

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

Answer»

Given,

Depth of tubewell = 280 m

Diameter of tubewell = 3 m

So radius = \(\cfrac32\) m

Volume of tubewell = πr²h

= \(\cfrac{22}7\times\cfrac94\times\)280

= 1980 m³

Curved surface area of tubewell = 2πrh

= 2\(\times\cfrac{22}7\times\cfrac{3}2\times\)280

= 2640 m²

∴ cost of sinking at rate Rs 3.60/m³ = 3.60 × 1980 = Rs. 7128.

∴ cost of cementing at rate Rs. 2.50/m² = 2.50 × 2640 = Rs. 6600.