The diameter of a roller 120cm long is 84cm. If its takes 500 complete

1.	The diameter of a roller 120cm long is 84cm. If its takes 500 complete revolutions to level a playground determine the cost of leveling at the rate of Rs. 25per square metre. (Use π = 22/7 )
Answer» 2r = 84cm ∴ r = 84/2cm = 42cm h = 120cm Area of the playground leveled in one complete revolution = 2πrh = 2 × 22/7 × 42 × 120 × 31680cm² ∴ Area of the playground = 31680 × 500cm² = (31680 x 500)/(100 x 100)m² = 1584m² ∴ Cost of leveling @ Rs 25 per square metre = Rs 1584 × 25 = 39600.

The diameter of a roller 120cm long is 84cm. If its takes 500 complete revolutions to level a playground determine the cost of leveling at the rate of Rs. 25per square metre. (Use π = 22/7 )

Answer»

2r = 84cm

∴ r = 84/2cm = 42cm

h = 120cm

Area of the playground leveled in one complete revolution = 2πrh

= 2 × 22/7 × 42 × 120 × 31680cm²

∴ Area of the playground = 31680 × 500cm²

= (31680 x 500)/(100 x 100)m² = 1584m²

∴ Cost of leveling @ Rs 25 per square metre = Rs 1584 × 25 = 39600.