The diameter of a roller 120cm long is 84cm. If it takes 500 complete revolutions to level a playground, determine the cost of levelling it at the rate of 30 paise per square metre.

Explanation

`2r = 84cm `
`r = (84)/(2cm) = 42cm`
` h = 120cm`
Area of the playground leveled in one complete revolution
` 2pirh = 2 xx( 22/7 )xx 42 xx 120 xx 31680cm^2`
Area of the playground
`31680 xx 500cm^2`
`(31680 xx 500)/(100 xx 100)m^2 `
`1584m^2`
Cost of leveling ` Rs 25` per square metre
` Rs 1584 xx 25`
`39600`.