How many cubic metres of earth must be dugout to sink a well 21 m deep and 6 m diameter? Find the cost of plastering the inner surface of the well at Rs. 9.50 per m2.
The inner diameter of a circular well is 3.5 m. It is 10 m deep. Find :
(i) inner curved surface area.
(ii) the cost of plastering this curved surface at the rate of Rs. 40 per m2.