Q12 of 24 Page 227

A heap of wheat is in the shape of a right circular cone, its base diameteris 9m. and height is 3.5m. Let us determine the total volume of wheat. Let us calculate the minimum quantity of plastic sheet to be required to cover up this heap of wheat [suppose π =3.14, √130 = 11.1]

Base diameter = 9 m


∴ base radius = 9/2 = 4.5 m


Height, h = 3.5 m


∴ volume of wheat,


= πr2h/3


= 3.14 × 4.52× 5/3


= 105.975 m3


Slant height,


l = √(4.52 + 3.52) = √(20.25 + 12.25) = 5.7 m


∴ Plastic sheet required to cover the wheat,


= πrl


= 3.14 × 4.5 × 5.7


= 80.541 m2


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