7th grade math either I’m dumb or this is wrong

We just started the introduction into circles and i have no idea how to do this.

Ihonestly have no clue if it's each or none.

The coverage of a base station of a telecommunication company forms a disk with a radius of (kilometers). let be the distance of a cellphone from a base station. assume that the location of cellphones in use are randomly uniformly distributed within the disk. calculate the mean and variance for the random variable.