ICSE Class X Math 2016 Solved Paper

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Question : 7
Total: 57
A certain number of metallic cones, each of radius 2‌cm and height 3‌cm are melted and recast into a solid sphere of radius 6‌cm. Find the number of cones.
Solution:  
‌‌ Let number of cones ‌=n
Volume of cones = Volume of sphere
=‌
1
3
Ï€
r2
h
×n
‌
=‌
4
3
Ï€
r3

n×‌
1
3
Ï€
×22
×3
‌
=‌
4
3
Ï€
×63

n‌=‌
216
3

n‌=72
Hence, no. of cones =72
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