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9.A road roller takes 750 complete revolutions to move once over to level a road. Find the area of the road if the diameter of a road roller is 84 cm and length is 1 m.

Answer :

Given,diameter of the road roller=84cm and length=1m.Also revolution=750

We have radius of roller r=\(\frac{84}2=42cm=0.42m\)

So, curved surface area of the roller=\(2\pi rh\)

\(=2\times \frac{22}7 \times 0.42 \times 1\)

\(=22.64 m^2\)

∴area levelled by the roller in 750 revolutions:

\(\qquad=(750\times 2.64)=1980m^2\)

Hence, the area of the road levelled=\(1980m^2\)