Question

A solid metallic cylinder whose height is four times of its base radius, is melted and casted into the spherical balls of same base. How many such balls are made?

Answer 1

Let the radius of cylinder be h and base radius be r.
But $h=4r$
Volume $=\pi r^{2}h$
$=\pi r^2\left(4r\right)=4\pi r^3$
and, the volume of a ball of radius $r=\frac{4}{3}\pi r^3$
$\therefore$ Number of balls so made $=\frac{4\pi r^3}{\frac{4}{3}\pi r^3}=3.$