question_answer 25)

                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:

                Diameter of the road roller = 84 cm \[\therefore \] Radius (r) of the road roller \[=\frac{84}{2}\,cm\,=\,42\,cm\] Length (h) of the road roller = 1 m = 100 cm \[\therefore \] Lateral surface area of the road roller \[=2\pi rh\] \[=2\times \frac{22}{7}\,\times 42\times 100\] \[=26,\,400\,c{{m}^{2}}\] \[\therefore \] Area of the road covered in 1 complete revolution \[=26,400\,c{{m}^{2}}\] \[\therefore \] Area of the road covered in 750 complete revolutions \[=26,\,400\times 750\,c{{m}^{2}}\] \[=1,98,00,000\,c{{m}^{2}}\] \[=1,980\,{{m}^{2}}\].