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

Here diameter, `d=84cm`

`r=d/2`=`84/2`=`42`cm

Height, h=120cm

Area covered in 1 complete revolution=`2xx22/7xxrxxh`

`2xx22/7xx42xx120`=`31680cm^2`

`therefore` area of the playground=`31680xx500 cm^2`

`15840000cm^2`

`15840000/10000 m^2`=`1584 m^2`

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