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

Explanation

Depth of tubewell `= 280 m`
Diameter of tubewell `= 3 m`
Radius of tubewell `= 3/2 m`
Volume of tubewell ,`V = pi r^2 h `
`V = 22/7 xx (3/2)^2 xx 280`
`V = 22/7 xx 9/4 xx 280`
`V = 22 xx9 xx 10`
Volume of tubewell,`V = 1980 m^3`
Curved surface area of tubewell ,` C.S.A = 2 pi rh `
`C.S.A = 2 xx 22/7 xx 3/2 xx 280`
`C.S.A = 22 xx 40 xx 3`
`C.S.A = 66 xx 40`
C.S.A of tubewell `= 2640 m^2`
Cost of sinking a tubewell at the rate of `= ₹ 3.60/m^3`
Cost of sinking a tubewell `=` Rate `xx`volume `= 3.60 xx 1980 = ₹ 7128`.
Hence, the cost of sinking a tubewell is `₹ 7128`
Cost of cementing its inner curved surface at the rate of `= ₹ 2.50` per square metre.
Cost of cementing `=` Rate `xx` inner curved surface `= 2.50 xx 2640 = ₹ 6600`.
Hence , the cost of cementing its inner curved surface is `₹ 6600`.