7, The inner diameter of a circular well is 4.2 m.It is 12 m deep. Fin

1.	7, The inner diameter of a circular well is 4.2 m.It is 12 m deep. Find () its inner curved surface areathe cost of plastering the inner curved surface at the rate of R 50 per m
Answer» Given height h = 12m.Given the diameter of the circular well d = 4.2 meter.Then the radius of the circular well r = d/2 = 4.2/2 = 2.1m. (1) Inner curved surface Area = 2πrh = 2 * 22/7 * (2.1) * 12 = 2 * 22 * 0.3 * 12 = 158.4m^2. (2) Given that cost of plastering per m^2 = 50. Then the cost of plastering of 158.4m^2 area = 158.4 * 50 = 7920.

7, The inner diameter of a circular well is 4.2 m.It is 12 m deep. Find () its inner curved surface areathe cost of plastering the inner curved surface at the rate of R 50 per m

Answer»

Given height h = 12m.Given the diameter of the circular well d = 4.2 meter.Then the radius of the circular well r = d/2 = 4.2/2 = 2.1m.

(1) Inner curved surface Area = 2πrh = 2 * 22/7 * (2.1) * 12 = 2 * 22 * 0.3 * 12 = 158.4m^2.

(2) Given that cost of plastering per m^2 = 50. Then the cost of plastering of 158.4m^2 area = 158.4 * 50 = 7920.