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.

Diameter of road roller, d = 84 cm 

Radius of road roller, $r = \frac{d}{2} = \frac{84}{2} = 42 cm$ 

Length of road roller,$h = 1 m = 100 cm$

The lateral surface area of the road roller $= 2\pi rh$

= $2\times \left(\frac{22}{7}\right)\times 42\times 100 = 26400 c{m}^2$

Area covered by road roller in 750 revolutions$= 26400\times 750c{m}^2 = 1,98,00,000 c{m}^2 = 1980 m^2$ $[\because 1 m^2 = 10,000 c{m}^2]$

Hence the area of the road is $1980 m^2$.