Question

A cylindrical rod, whose height is $8$ times its radius, is melted and cast into spherical balls of the same radius. The total number of spherical balls so formed, is

• A. $3$
• B. $4$
• C. $6$
• D. $8$

Answer 1

The correct option is C $6$

Let radius of cylindrical rod be $R$, then its height will be $8R$
Volume of cylinder $=\pi R^2\left(8R\right)$

Volume of one sphere $=\frac{4}{3}\pi R^3$

Let $n$ spheres can be made, then $n\times \frac{4}{3}\pi R^3$ = $\pi R^2\left(8R\right)$

$\therefore n=6$