Answer:
236.22 cubic centimeters
Explanation:
We need to find volume of 3 tennis balls and subtract it from volume of the cylinder to get our answer.
Volume of sphere (tennis ball) =

Note: Radius is half of diameter, which is r = 6.7/2 = 3.35
Volume of 3 tennis balls =

Volume of Cylinder =

Note: radius is 3.35 and height is diameter of 3 tennis balls stacked on top of each other, so height is 6.7 * 3 = 20.1
Hence,
Volume of Cylinder =

amount of space not taken up = 708.66 - 472.44 = 236.22 cubic centimeters