A cylindrical tub of radius 12 cm contains water to a depth of 20 cm. A spherical ball is dropped into the tub and the level of the water is raised by 6.75 cm. Find the radius of the ball.
Given, the radius of the cylindrical tube, r = 12cm
Level of water raised in tube, h = 6.75cm
Volume of cylinder = πr2 h
= π (12)2 × 6.75 cm3
----------(i)
let r be the radius of a spherical shell balls
volume of the sphere = 
-------(ii)
∵ volume of cylinder = volume of spherical ball
⇒ r = 9cm
∴ radius of spherical ball, r = 9cm
20