CBSE 10th Class Mathematics
Past year question paper
Year 2020
SET 1, Code Number – 30/5/1
Question Number – 38
hemisphere surmounted by a right circular cone of same radius
cone area and volume problem
Deepak BoraNewbie
A solid toy is in the form of a hemisphere surmounted by a right circular cone of same radius. The height of the cone is 10 cm and the radius of the base is 7 cm. Determine the volume of the toy. Also find the area of the coloured sheet required to cover the toy. [ Use π = 22/7 and √149 = 12.2
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Volume of the toy = Volume of cone + Volume of hemisphere
Cone: r = 7 cm, h = 10 cm
Hemisphere: r = 7 cm
Volume of toy = [1/3 (πr²h)] + [2/3 (πr³)]
= { 1/3 (πr² [h+ 2r] ) }
= { 1/3 (22 × 7 × 24 ) }
Volume of toy = 1232 cm³
Area of coloured sheet required to cover the toy = CSA of cone + CSA of hemisphere
= πrl + 2πr²
= πr [ l + πr ]
= [22 / 7] × 7 [12.2 + 14]
l² = 10² + 7²
l = 100 + 49
l = √149
l =12.2
= 22 × 26.22
= 576.4 cm²