AMO 2021 - Secondary 2 (Grade 8) Question 9

Question 9

A circular coffee filter has radius 3 inches. Linda cuts out one-third of the disk, as shown, and rolls that sector into a cone without overlap. What is the radius of the cone’s base?

Question illustration

$\frac12$ inch
$\frac{3\pi}{2}$ inches
$\pi$ inches
1 inch
$\frac\pi2$ inches