Last updated at Dec. 8, 2016 by Teachoo

Transcript

Ex 13.3, 3 A 20 m deep well with diameter 7 m is dug and the earth from digging is evenly spread out to form a platform 22 m by 14 m. Find the height of the platform. Here, shape of well is in form of cylinder & shape of platform will be in shape of cuboid. Hence, Volume of well = Volume of platform So , Volume of cylinder = Volume of cuboid Volume of cylinder Diameter = 7 m radius = r = ๐ท๐๐๐๐๐ก๐๐/2 = 7/2 m & Height = h = 20 m Volume of cylinder = ๐๐2โ = 22/7ร(7/2)^2 ร20 = 22/7ร7/2ร7/2ร20 = 770 m3 Volume of cuboid Length = l = 22 m Breadth = b = 14 m Let Height = h m Volume of cuboid = lbh = 22 ร 14 ร h Now, Volume of cylinder = Volume of cuboid 770 = 22 ร 14 ร h 770/(22 ร 14) = h h = 770/(22 ร 14) h = 770/(22 ร 14) h = 2.5 m Hence, height of platform = 2.5 m

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Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He provides courses for Mathematics from Class 9 to 12. You can ask questions here.