Question

how many cubic meter of earth must be dug to construct a well 7meter deep and diameter 2.8 meter?

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:

Find the radius:

Radius = Diameter ÷ 2

Radius = 2.8 ÷ 2 = 1.4 m

Find the volume:

Volume = πr²h

Volume = π (1.4)²(28)

Volume = 172.48 m²

Find the inner surface area:

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

Find the cost of plastering:

1 m² = ₹4.50

30.8 m² = 4.5 x 30.8 = ₹ 138.60

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

Answer 2

Height=7 m and daimeter=2.8 m

r=d/2=1.4

Volume=πr²h=22/7×(1.4)²×7=43.12m²