Question

4. The diameter of a roller is 42 cm and its length is 120 cm. It takes 500 complete
revolutions to move once over to level a playground. Find the area of the playground.

Answer 1

Answer:

We have the diameter of a cyclindrial roller = 42 cm

⇒ The radius of cyclindrical roller (r) = 42 / 2 = 21 cm

Length of a cyclindrical roller (h) = 120 cm

Curved surface of the roller = 2πrh = 2 × 22 / 7 × 21 × 120 = 15840 cm2

= 15840 / 10000 m2 = 1.584 m2

Area covered by the roller in one complete revolution .

= curved surface of the roller = 1.584 m2

∴ Area of the playground = Area covered by the roller in 500 complete revolutions

= 500 × 1.584

= 792 m2