What's the Resistance in a Circular Pan with a Metal Disk?

[kjintonic]

Homework Statement

A circular pan of radius b has a plastic bottom and metallic side wall of height h. It is filled with a solution of resistivity p. A metal disk of radius a and height h is placed at the center of the pan. The side and disk are perfect conductors. what's the resistance measured from the side of the disc. the answer is suppose to be (p*ln(b/a))/(2'pie'L)

Homework Equations

R= pL/A

The Attempt at a Solution

I kinda don't know how to start. the solution makes me confused

 

[Redbelly98]

What would be the resistance of a thin ring, with height h, radius r, and thickness Δr?

Once you get that, think of how to combine many such rings to fill the space between r=a and r=b.