Question

a road roller has a diameter 84 cm and its width is 1.2 metre if it takes 500 complete revolutions to level a playground find the area of the playground and also find the cost of levelling the playground at the rate of 50% per metre square

Answer 1

Solution :-

Diameter of roller = 84 cm 
Radius = 84/2 = 42 cm or 0.42 m

Width or height = 1.2 m 

Roller is in the shape of a cylinder.

Area of roller = Curved surface area of cylinder

Curved surface area of cylinder = 2πrh

⇒ 2*22/7*0.42*1.2

⇒ 22.176/7

= 3.168 m²

Area of 1 revolution = Area of roller = 3.168 m²

Area of 500 revolution = Area of playground = 3.168 × 500

= 1584 m²

So, the area of the playground is 1584 m²

Cost of levelling the playground should be Rs. 50 per sq m instead of wrongly written 50 % per square meter.

Total cost of levelling the playground = 50 *1584

= Rs, 79200 

Answer.