In a building, there are 24 cylindrical pillars. For each pillar, radius is 28 cm and height is 4 m. Find the total cost of painting the curved surface area of the pillars at the rate of ₹ 8 per m².

Given:

Number of cylindrical pillars = 24

Radius of each pillar = 28 cm = 0.28 m

Height of each pillar = 4 m

As we know, the curved surface area of cylinder = 2πrh

Curved surface area of 1 pillar =

$= 2 \times \dfrac{22}{7} \times 0.28 \times 4\\[1em] = \dfrac{49.28}{7}\\[1em] = 7.04 m^2$

Total curved surface area for 24 pillar = 24 x curved surface of 1 pillar

= 24 x 7.04 m²

= 168.96 m²

Rate of painting = ₹ 8 per m²

Total cost = Total curved surface area x Rate of painting

= 168.96 x ₹ 8

= ₹ 1,351.68

Hence, the total cost of painting the pillars is ₹ 1,351.68.