Question

A cylindrical tube of radius $12cm$ contains water to a depth of $20cm$. A spherical form ball is dropped into the tube and thus the level of water is raised by $6.75cm$. What is the radius of the ball?

Answer 1

Volume of spherical ball= volume of water with h=$6.75cm$

$\begin{array}{c}\frac{4}{3}\pi r^3=\pi r^2\times 6.75\\ =\frac{4}{3}\pi r^3=\pi {\left(12\right)}^2\times 6.75\\ =r^3=\frac{{\left(12\right)}^2\times 6.75\times 3}{4}\\ =r^3=729\\ =r=9cm\left(radiusofball\right)\end{array}$