The diameter of a roller 84 cm long is 1.5 m. If it takes 100 revolutions to level a playground, find the cost of levelling this ground at the rate of ₹ 0.50 per square metre.
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Solution
We have d = 1.5 m, r=1.52=1520m=34m
and h=84cm=84100m ∴ Area covered in 1 revolution =2πrh=2×227×34×84100=44×9100m2 ∴ Area covered in 100 revolutions =100×44×9100=396m2 ∴ Cost of levelling the playground =₹0.50×396=₹198