If the radius of a sphere increases from 3 feet to 9 feet, by how many cubic feet does the volume of the sphere increase? 967 ft3 A 1087 ft3 936 ft 0

The volume of a sphere is given by:
[tex]V=\frac{4}{3}\pi r^3[/tex]The original sphere, with radius r=3, has volume:
[tex]\begin{gathered} V=\frac{4}{3}\pi(3)^3 \\ =36\pi \end{gathered}[/tex]The second sphere, with radius r=9, has volume:
[tex]\begin{gathered} V=\frac{4}{3}\pi(9)^3 \\ =972\pi \end{gathered}[/tex]To find how much the volume increased we substract the first volume to the second one:
[tex]972\pi-36\pi=936\pi[/tex]Therefore the v