Answer:
The volume of the area not occupied by the tennis balls is 12.28 cubic inches.
Step-by-step explanation:
It is given that tennis balls with a diameter of 2.5in are sold in cans of three. the can is a cylinder.
Radius of ball = Radius of can = 
Height of can = 
The volume of sphere is

where, r is radius of sphere.
The volume of a tennis balls is



Volume of three tennis balls is

The volume of cylinder is

The volume of can is



The volume of the area not occupied by the tennis balls is
Volume = Volume of cylinder - Volume of three tennis balls
= 36.82 - 24.54 = 12.28 inches
Therefore, the volume of the area not occupied by the tennis balls is 12.28 cubic inches.