Question

The diameter of roller 1.5 m long is 84 cm. If it takes 100 revolutions to level a playground, find the cost of levelling this ground at the rate of 50 paise per square metre.

Answer 1

The cost of leveling is Rs. 198.

Length of the roller = 1.5 m

Diameter of the roller = 84 cm = 0.84 m

Radius of the roller = D/2 = 0.84/2 = 0.42

Area covered by the roller in one revolution = CSA of roller

CSA = 2πrh

= 2 x 22/7 x 0.42 x 1.5

= 0.12 x 22 x 1.5

Now,

Area of playground = 100 x Area covered by the roller in one revolution

= (100 x 0.12 x 22 x 1.5)

= 396 m²

Cost of leveling 1m² = 50P

= 50/100 = 1/2

Cost of leveling 396m² = 1/2 × 396

= 198

Thus, the cost of leveling is Rs. 198.