Solution;

Given radius of the glass jar, R = 8 cm

Diameter of the sphere = 12 cm

Radius of the sphere, r = 12/2 = 6 cm

When the sphere is removed from the jar, volume of water decreases.

Let h be the height by which water level will decrease.

Volume of water decreased = Volume of the sphere

R²h = (4/3)r³

8²h = (4/3)6³

h = (4/3)×6×6×6/(8×8)

= 18/4 = 9/2 = 4.5 cm

Hence the height by which water level decreased is 4.5 cm.