Question

The cost of painting the outer surface of a cylindrical chimney, 5 m long is ₹220. If the cost of painting one square metre area is ₹ 5, find the diameter of the chimney.​

Answer 1

Step-by-step explanation:

The area painted is the curved surface area of the cylinderical chimney.

Curved surface area of cylinder = 2πrh

Given, h = 5m

Total cost of painting = Rs 220

Rate of painting = Rs 5/m²

Total cost of painting = Area painted × Rate of painting

220 = 2πrh × 5

2πrh = 220/5 = 44

2 × 22/7 × r × 5 = 44

r = (44×7) / (22×2×5) = 1.4 m

Diameter = 2×r = 2.8 m