A spherical shell is formed by taking a solid sphere of radius 20.0 cm and hollowing out a spherical section from the shell’s interior. Assume the hollow section and the sphere itself have the same center location (that is, they are concentric).
(a) If the hollow section takes up 90.0 percent of the total volume, what is its radius?
(b) What is the ratio of the outer area to the inner area of the shell?