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What is the least number of solid metallic spheres, each of 6 cm diameter, that should be melted and recast to form a solid metal cone whose height is 45 cm and diameter 12 cm?

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Question

What is the least number of solid metallic spheres, each of 6 cm diameter, that should be melted and recast to form a solid metal cone whose height is 45 cm and diameter 12 cm?

Sum
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Solution

Let the number of solid metallic spheres be 'n'

Volume of 1 sphere 

= `4/3pi(3)^3` 

Volume of metallic cone 

= `1/3pi6^2 xx 45` 

`n = "Volume of metal cone"/"Volume of 1 sphere"` 

`=> n = (1/3pi6^2 xx 45)/(4/3pi(3)^3)` 

`=> n = (6 xx 6 xx 45)/(4 xx 3 xx 3 xx 3)` 

`=>` n = 15 

The least number of spheres needed to form the cone is 15 

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Chapter 20: Cylinder, Cone and Sphere - Exercise 20 (G) [Page 316]

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Selina Concise Mathematics [English] Class 10 ICSE
Chapter 20 Cylinder, Cone and Sphere
Exercise 20 (G) | Q 1. | Page 316

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