A cylindrical bucket with base radius 15 cm is filled with water up to a height of 20 cm. A heavy iron spherical ball of radius 9 cm is dropped into the bucket to submerge completely in the water. Find the increase in the level of water.
Given,
Radius of spherical ball = 9 cm
Volume of spherical ball = 
πr3 = 
Radius of cylinder = 15 cm
Let the increase in level = h cm
= 
π × 729 = π × 15 × 15 × h
= h = 
20