Class 9 | Chapter 13 | Surface areas and Volumes | Exercise 13.8

Example 9: Twenty seven solid iron spheres, each of radius r and surface area S are melted to form a sphere with surface area S′. Find the

(i) radius r ′ of the new sphere, (ii) ratio of S and S′.

Sphere – Volume

Volume of sphere = 4πr³/3

Volume of hemisphere = 2πr³/3

r = base radius of sphere

It is recommended to understand the core concept of area, surface area and volume before we attempt any question based on these concepts.