Question

A cylindrical rod of iron whose height is four times its radius is melted and cast into the spherical balls of the same radius then the number of balls is

• A. 2
• B. 3
• C. 4
• D. 8

Answer 1

The correct option is B 3

Let the radius of cylindrical rod is r then height is 4r (given)

Then volume of cylindrical rod =$2\pi r^2\left(4r\right)=4\pi r^3$

This rod melt and cast into spherical ball radius r

Then volume of ball=$\frac{4}{3}\pi r^3$

So number of balls =$\frac{4\pi r^3}{\frac{4}{3}\pi r^3}=3$