Twenty cylindrical pillars of the Parliament House are to be cleaned. If the diameter of each pillar is 0.50 m and height is 4 m. What will be the cost of cleaning them at the rate of Rs. 2.50 per square metre?
Given,
Diameter of one pillar = .50m
Radius of pillar = 
Height of each pillar = 4m
Curved surface area of one pillar = 2πrh = 
2
Area of 20 pillars = 20×6.28 = 125.60 m2
Cost of cleaning 1 m2 area = Rs. 2.50
∴cost of cleaning 125.60 m2 = 125.60×2.50 = Rs 314.28.
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