Question

The figure shows there tennis balls in a can with each tennis ball....

Answer 1

Can:
The formula for the volume of a cylinder is V = πr²h. So h = 3d = 3(2.5)
V = π1.25²(3(2.5)) = π1.25²(7.5) = 36.816 in.³

Tennis balls:
The formula for the volume of a sphere is V = (4/3)πr³. 
V(3 tennis balls) = (4/3)πr³(3) = (4/3)π1.25³(3) = 8.181(3) = 24.544 in.³

Air inside the can:

V (can) - V (3 tennis balls) = 36.816 - 24.544 = 12.272 in.³ of air