In general, one can obtain the volume of a sphere and a cube using the formulas below
[tex]\begin{gathered} V_{cube}=l^3 \\ l\rightarrow\text{ side of the cube} \\ V_{sphere}=\frac{4}{3}\pi r^3 \\ r\rightarrow\text{ radius} \end{gathered}[/tex]
In our case, we need to subtract the volume of the hollow sphere from the volume of the cube, as shown below
[tex]\begin{gathered} V_{cube}=18^3 \\ and \\ V_{sphere}=\frac{4}{3}\pi(9)^3 \\ \Rightarrow V_{foam}=V_{cube}-V_{sphere} \\ \Rightarrow V_{foam}=2778.371... \end{gathered}[/tex]
Rounding to the nearest hundredth,
[tex]\Rightarrow V_{foam}\approx2778.37[/tex]
The answer is 2778.37in^3
