Ex 9.2, 9 - Chapter 9 Class 8 Mensuration

Last updated at April 16, 2024 by

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Ex 9.2, 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, Length of roller = h = 1 m & Diameter of the roller = 84 cm ∴ Radius of the roller = r = 84/2 cm = 42 cm = 𝟒𝟐/𝟏𝟎𝟎 m Given, the roller takes 750 complete revolutions to level the whole road ∴ Area of road = 750 × Area covered in 1 revolution = 750 × lateral surface area of cylinder = 750 × 𝟐𝝅𝒓𝒉 = 750 ×2×22/7×42/100×1 = 750 ×2×22×6/100×1 = (1500 × 132)/100 = 15 × 132 = 1980 m2

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.