(13) Consider two nested spherical shells. The inner spherical shell is an insulator (inner radius a, outer radius b) with a net charge of +2Q distributed uniformly through its volume. The outer spherical shell (inner radius c, outer radius d) is a conductor with a net charge of -3Q. A point charge +Q is placed at the center of the spheres at r=0. (a) What is the charge distribution on the inner and outer surface of the conducting sphere, and why? (b) Use Gauss's Law to determine the electric field for two regions: b < r < c and c < r < d.