Question

A spherical ball of diameter 21 cm is melted and recast into cubes, each of side 1 cm. Find the number of cubes so formed.

Answer 1

Diameter of the spherical ball= 21 cm

Radius of the ball $=\frac{21}{2}cm$
Volume of spherical ball $=\frac{4}{3}{\mathrm{\pi r}}^3=\frac{4}{3}\times \frac{22}{7}\times \frac{21}{2}\times \frac{21}{2}\times \frac{21}{2}=11\times 21\times 21=4851{\mathrm{cm}}^3$
Volume of each cube $=1^3=1c{m}^3$

Number of cubes = $\frac{Volumeofsphericalball}{Volumeofeachcube}=\frac{4851}{1}=4851$