Answer: a) see attach file; b) E=0; c)E=-1.65* 10^6 N/C
Explanation: In order to solve this problem we have to use the gaussian law which is given by:
∫E*dr=Q inside/εo
E for r=8 cm is located inside the conducting shell so E=0.
For r=13 cm we have to use above gaussian law considering the total charge inside a gaussian surface with radius equal to 0.13 m. ( see attach)
