Pls help with 3 and 4

Problem 3: Insulating sphere An insulating sphere with radius R has a nonuniform, but spherically symmetric, distribution of charge density p(r) given by p(r) = Po(1 - Ar/3R), for r S R FWUS . 308-0 p(r) = 0 for r > R where po is a positive constant. a) Find the total charge contained in the sphere. b) Obtain an expression for the electric field in the region r > R. c) Obtain an expression for the electric field in the region r S R. d) Graph the electric field magnitude E as a function of r. Problem 4 A small sphere with a mass of m and carrying a charge of q hangs from a thread near a very large, charged insulating sheet, as shown in figure below. The charge density on the surface of the sheet is uniform and equal to -o, where o is a positive constant. Find the angle of the thread