What are the assumptions for solving the charged conducting disk problem?

[hairey94]

Homework Statement

Four electrons are released onto a thin aluminum disc of diameter 10𝑚𝑚. If the disc is initially neutral, calculate the electric potential at the center of the disc and the energy stored in the disc.

Relevant Equations

V = kQ/r

Not sure how the problem set up initially as no diagram was provided in the question. Please help me to start with the solution. Your assumptions and educated guess are appreciated.

 

[haruspex]

I have a nasty feeling the question setter expects you to assume the existing electrons in the disc all stay put.
But maybe not... take a look at https://blog.richmond.edu/physicsbunn/2013/03/01/the-charged-conducting-disk-again/.