Q21 of 22 Page 258

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

Given, Number of cylindrical pipes(n) = 24

Radius of each pipe = r = 28 cm = 0.28 m


height of pipe = h = 4m


Area of painting = n × curved surface area of cylindrical pipe




= 168.96 m2


As, cost of 1 m2 = Rs. 8


So, cost of 168.96 m2 = 8 × 168.96 = Rs. 1351.68


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