A solid conducting sphere of radius 2.00 cm has a charge of 8.60 µC. A conducting spherical shell of inner radius 4.00 cm and outer radius 5.00 cm is concentric with the solid sphere and has a charge of -3.10 µC. Find the electric field at the following radii from the center of this charge configuration:
(a) r = 1.00 cm
(b) r = 3.00 cm
(c) r = 4.50 cm
(d) r = 7.00 cm