I'm trying to tease out the different ways to understand racism through a series of thought experiments.

Here's the first one.

The Experiment

A shopkeeper knows that a certain percentage of all his customers are thieves.

Could be 5%, could be 10%. Let's just call it percentTotal, or pT.

He keeps record of all the thefts. Looking over, he notices the following.

For a certain group of customers, who all share the same race X, the percentage of thefts differs from entire customer base as a whole.

It might be higher than pT, or it might be lower. We're not gonna say.
We're just gonna call it percentageRace, or pR.

The question is this: Could pR possibly be so much bigger than pT that it would allow the shopkeeper to ban everyone from race X from his shop without being racist?

If so, how much bigger does pR have to be than pT?
If 50% of customers of race X where thieves compared to only 5% of the total, would it be racist to ban them from the shop?

And, are there other factors that would change the conclusions?

What do you think?
All considerations and reflections appreciated :)