Ex 13.2, 4 - The diameter of roller is 84 cm and its length - Area Of Cylinder


  1. Chapter 13 Class 9 Surface Areas and Volumes
  2. Serial order wise
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Ex 13.2, 4 The diameter of a roller is 84 cm and its length is 120 cm. It takes 500 complete revolutions to move once over to level a playground. Find the area of the playground in m2? [๐ด๐‘ ๐‘ ๐‘ข๐‘š๐‘’ ๐œ‹= 22/7] Roller is of form cylinder Radius = ๐ท๐‘–๐‘Ž๐‘š๐‘’๐‘ก๐‘’๐‘Ÿ/2 = 84/2 = 42 cm Area of roller = Curved surface of cylinder = 2ฯ€rh = (2ร—22/7ร—42ร—120) cm2 = 31680 cm2 Area of 1 revolution = Area of roller = 31680 cm2 Area of 500 revolution = 500 ร— 31680 cm2 Area of playground = 15840000 cm2 = 15840000 ร—1/(100 ) ร—1/(100 )m2 = 1584 m2

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.
  • Albert Einstien's image
    Sir can you please tell me that in chapter surface areas and volumes exercise no.13.2 . Question no.4 how did you take area of 1 revolution=area of roller....i have not understood only this single line...can you please tell my answer
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  • Ayush Srivastava's image
    Ayush Srivastava
    Sept. 3, 2017, 6:40 p.m.
    Diameter and length of a roller are 84 cm and 120 cm respectively.In how many revolutions,can the roller level the playground of area 1,584 m^2?
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