rl - rubber layer, s - sphere, b - ball
[tex]V_{rl}=V_b-V_s\\
V=\dfrac{4}{3}\pi R^3\\\\\\
V_{rl}=\dfrac{4}{3}\cdot3.14\cdot22^3-\dfrac{4}{3}\cdot3.14\cdot18^3\\
V_{rl}=\dfrac{4}{3}\cdot3.14(10648-5832)\\
V_{rl}=\dfrac{4}{3}\cdot3.14\cdot4816\\
V_{rl}=20162.99\text { in}^3
[/tex]