# Mensuration-13

### From Homeworkwiki

**The diameter of a roller 120 cm long is 84 cm. If it takes 500 complete revolutions to level a playground, determine the cost of leveling at the rate of $ 1.75 per sq. m.**

**Solution:** The diameter of the roller = 84 cm

Therefore, radius of the roller = 42 cm

Length of the roller = 120 cm

When the roller makes one complete revolution, the area of the playground leveled = 2π r h

= 2 x 22/7 x 42 x 120 sq. cm

= 2 x 22 x 6 x 120 sq. cm

Therefore, in 500 revolutions, the area of the playground leveled by the roller

= 2 x 22 x 6 x 120 x 500 sq. cm

= (2 x 22 x 6 x 120 x 500) / (100 x 100) sq. m

= 1584 sq. m

Cost of leveling at the rate of $ 1.75 per sq. m

= $ 1584 x 1.75 = $ 2772