Physics Resistance help

Hey! im attempting some of the "harder" questions my teacher has set for me. i have done all but one and this one has completely stumped me. im wondering if someone could point me in the right direction. I posted in physics first but a responder suggested i see if the mathematicians could solve this. This is all the information i have to go on

Question:

"A hollow sphere made of graphite (ρ=25×10^-5Ωm) has an outside radius of 100mm and an inside radius of 99mm

Calculate a rough value for the resistance of this sphere when connected at opposite poles."