In a building, there are 24 cylindrical pillars. For each pillar, the radius is 28 m, and the height is 4 m. Find the total cost of painting the curved surface area of the pillars at the rate of ₹ 8 per m2.
Radius of cylindrical pillar, r = 28 cm = 0.28 m, height = h = 4 m
curved surface area of a cylinder = 2πrh
curved surface area of a pillar = `2 xx 22/7 xx 0.28 xx 4` = 7.04 m2
curved surface area of 24 such pillar = 7.04 × 24 = 168.96 m2
cost of painting an area of 1 m2 = Rs. 8
Therefore, cost of painting 1689.6 m2 = 168.96 × 8 = Rs. 1351.68.
Concept: Surface Area of a Cuboid
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