In a building, there are 24 cylindrical pillars. The radius of each pillar is 28 cm and height is 4 m. Find the total cost of painting the curved surface area of all pillars at the rate of ₹8 per $$\text{m}^2$$​.

Correct option is D

Given:

Number of pillars = 24

Radius of each pillar = 28 cm = 0.28 m

Height of each pillar = 4 m

Cost of painting = ₹8 per m²

Formula Used:

Curved surface area (CSA) = 2πrh

Total cost = Total area × Rate per m²

Solution:

CSA of one pillar = $$2 \times \frac{22}{7} \times 0.28 \times 4$$​​

​$$= \frac{44}{7} \times 1.12\\ \ \\ = \frac{44 \times 1.12}{7}\\ \ \\ = \frac{49.28}{7} = 7.04 \text{ m}^2$$​​

Total CSA of 24 pillars = $$24 \times 7.04 = 168.96 \text{ m}^2$$​​

Total cost = 168.96 × 8 = ₹1351.68