This question is basically just asking you to take the volume of the entire ball and subtract the volume of the core (the part that's not polyurethane) to find the volume of the polyurethane.
The formula for the volume of a sphere is [tex] \frac{4}{3} \pi r^{3} [/tex] where r = the radius. First, let's find the volume of the whole sphere.
[tex]V=\frac{4}{3} \pi 9^{3} [/tex]
[tex]V=\frac{4}{3} \pi 729 [/tex]
[tex]V=\pi 972 [/tex]
Now let's find the volume of the inner core.
[tex]V=\frac{4}{3} \pi 6^{3} [/tex]
[tex]V=\frac{4}{3} \pi 216 [/tex]
[tex]V=\pi 288 [/tex]
972π - 288π = 684π
Use 3.14 for π and we get 684*3.14 = 2147.76 in³.
