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


Inner radius (r) of circular well = m

= 1.75 m


Depth (h) of circular well = 10 m


(i) Inner curved surface area = 2πrh


= 2 * * 1.75 * 10 m2


= (44 × 0.25 × 10) m2


= 110 m2


Therefore, the inner curved surface area of the circular well is 110 m2


(ii) Cost of plastering 1 m2 area = Rs 40


Cost of plastering 100 m2 area = Rs (110 × 40)


= Rs 4400


Therefore, the cost of plastering the CSA of this well is Rs 4400


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