Question

A solid metallic sphere of radius 8 cm is melted and recast into spherical balls each of radius 2 cm. Find the number of spherical balls obtained.

Answer 1

Volume of big sphere=volume of 1 small sphere $\times$ n [n is the number of small spherical balls]
$\frac{4}{3}\pi r^3=n\times \frac{4}{3}\pi R^3$
$8\times 8\times 8=n\times 2\times 2\times 2$
$\frac{512}{8}=n$
n=64