The diameter of roller 1.5 m long is 84 cm. If it takes 100 revolutions to level a playground, find the cost of levelling this ground at the rate of 50 paise per square metre.
Given,
Diameter of roller = 84 cm
So radius of roller = 
Length of roller = 1.5 m
Area covered by roller in one revolution = 2πrh =
2
Area covered by it in 100 revolution = 100×3.96 = 396 m2
Cost of levelling 1m2 area = Rs. .50
∴cost of levelling 396m2 = .50×396 = Rs. 198
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