Here, r = 3. 5/ 2 m , h = 10 m

(i) Inner curved surface area of the well

= 2πrh = 2 × 22/ 7 × 3. 5 /2 × 10m^{2}

= 22 × 5 m^{2} = 110 m^{2} Ans.

(ii) Cost of plastering 1 m^{2} = Rs 40

∴ Cost of plastering the curved surface area of the well

= Rs 110 × 40 **= Rs 4400 Ans**