Question

The inner diameter of a circular well is 3.5 m. It is 10 m deep. Find 

(i) its inner curved surface area, 

(ii) the cost of plastering this curved surface at the rate of Rs 40 per m²

Answer 1

Here, r = 3. 5/ 2 m , h = 10 m 

(i) Inner curved surface area of the well 

= 2πrh = 2 × 22/ 7 × 3. 5 /2  × 10m² 

= 22 × 5 m² = 110 m² Ans. 

(ii) Cost of plastering 1 m² = Rs 40 

∴ Cost of plastering the curved surface area of the well 

= Rs 110 × 40 = Rs 4400 Ans