Question

how many meters of earth must be dug to dig a well 32m deep with diameter 7m? Find the cost of plastering it's inner surface at $ 4.5per m2


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Answer 1

Answer:

172.48 m² of earth needs to be dug out and the cost of plastering is ₹ 138.60

Step-by-step explanation:

Radius = Diameter ÷ 2

Radius = 2.8 ÷ 2 = 1.4 m

Volume = πr²h

Volume = π (1.4)²(28)

Volume = 172.48 m²

Surface area = πr² + 2πrh

Surface area = π(1.4)² + 2π(1.4)(2.8)

Surface area = 6.16 + 24.64

Surface area = 30.8 m²

1 m² = ₹4.50

30.8 m² = 4.5 x 30.8 = ₹ 138.60