Question

A cylindrical rod of iron whose radius is one-fourth of its height is melted and cast into spherical balls of the same radius as that of the cylinder. What is the number of sphericals balls?

• A. $2$
• B. $3$
• C. $4$
• D. $5$

Answer 1

The correct option is B $3$

Let radius of cylindrical rod $=r$

$\Rightarrow$ height $=4r$

Volume of cylindrical rod $=\pi r^{2}h$

$=\pi r^2\left(4r\right)$

$=4\pi r^3$

Volume of spherical balls of radius $r=\frac{4}{3}\pi r^3$

No. of balls $=\frac{4\pi r^3}{\frac{4}{3}\pi r^3}=3balls$