# Thread: geometry homework

1. ## geometry homework

how many cubic inches of material are needed for a solid rubber ball with a diameter of 3 inches?

2. Originally Posted by hamadouousmane
how many cubic inches of material are needed for a solid rubber ball with a diameter of 3 inches?
The volume of a sphere is

$V=\frac{4}{3} \pi r^3$

$D=2r$

so $r=\frac{3}{2}in$

$V==\frac{4}{3} \pi \left( \frac{3}{2}in \right)^3=\frac{4 \pi}{3}\frac{27}{8}in^3 =\frac{9\pi}{2} in^3$