Find the cost of plastering the inner surface of a well at Rs 9.50 per

1.	Find the cost of plastering the inner surface of a well at Rs 9.50 per m2, if it is 21 m deep and diameter of its top is 6 m.
Answer» We have, Height of cylinder = 21m Diameter of cylinder = 6m Radius of cylinder = 6/2 = 3m Curved surface area of cylinder = 2πrh = 2 × 22/7 × 3 × 21 = 396 m² ∴ Cost of plastering the inner surface at the rate of Rs 9.50 per m² = 396 × 9.50 = Rs 3762

Find the cost of plastering the inner surface of a well at Rs 9.50 per m2, if it is 21 m deep and diameter of its top is 6 m.

Answer»

We have,

Height of cylinder = 21m

Diameter of cylinder = 6m

Radius of cylinder = 6/2 = 3m

Curved surface area of cylinder = 2πrh

= 2 × 22/7 × 3 × 21

= 396 m²

∴ Cost of plastering the inner surface at the rate of Rs 9.50 per m² = 396 × 9.50 = Rs 3762