Question

A cylinder is made of lead whose radius is $4$ $cm$ and height is $10$ $cm.$ By melting this, how many spheres of radius $2$ $cm$ can be formed?

Answer 1

Let the number of spheres be $x$.

Since, Volume will be same.

Therefore,

$\pi r_c^2{h}_c=x\times \frac{4}{3}\pi r_s^3$

$4^2\times 10=x\times \frac{4}{3}\times 2^3$

$4\times 10=x\times \frac{1}{3}\times 8$

$1\times 5=x\times \frac{1}{3}$

$x=15$.