NCERT - Mathematics

Book: NCERT - Mathematics

Chapter: 11. Mensuration

Subject: Maths - Class 8th

Q. No. 9 of Exercises 11.3

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9

A road roller takes 750 complete revolutions to move once over to level a road. Find the area of the road if the diameter of a road roller is 84 cm and length is 1 m.

Given: Diameter of road roller = 84 cm


Radius of road roller = 42 cm


Length of road roller, h = 1 m = 100 cm


Curved surface area of road roller = 2 π r h


= 2 × 22/7 × 42 × 100


= 26400 cm2


Area covered by road roller in 750 revolutions = 26400 × 750


= 1,98,00,000 cm2 or 1980 m2


the area of the road is 1980 sq. m.


9

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