In a can of tennis balls that is exactly three balls high, which is greater, the volume of the balls or the volume of the air around the balls? (Disregard the thickness of the balls.)

Here’s a cross-section of the can with 3 balls in it.

The volume of one tennis ball is 4/3

*r*^{3}, so all three are 4*r*^{3}.The volume of the cylinder is

*r*^{2}· 6*r*= 6*r*^{3}.The volume of air around the balls, thus is 2

*r*^{3}.Thus the volume of air is only half the volume of the balls.