The Volume of the model sphere is given as
[tex]V_{\text{sphere}}=\frac{4}{3}\pi r^3[/tex]
Given that the diameter is 5inches, the radius will be
[tex]\begin{gathered} \text{diameter,d}=2\times radius \\ r=\frac{d}{2}=\frac{5}{2}\text{inches} \\ r=2.5\text{inches} \end{gathered}[/tex]
substituting r in the formula will give
[tex]\begin{gathered} V_{\text{sphere}}=\frac{4}{3}\times3.14\times(2.5)^3 \\ =\frac{4}{3}\times3.14\times76.765625 \\ =\frac{964.17625}{3} \\ =321.3922\text{cubic inches} \end{gathered}[/tex][tex]V_{\text{sphere}}=321.39\text{cubic inches}[/tex]
Hence, the volume of the model sphere is approximately 321.39 cubic inches