Question

According to Wikipedia: "Racism is the view that among human beings there is a necessary connection between their origin and certain character traits, or sometimes intellectual abilities, or sometimes styles of movement and walking, so that the individual is judged not according to his personal uniqueness but only according to his belonging to a group."
If I own a business and am afraid and refuse to employ Arabs because I know of cases in which Arab workers murdered their coworkers for nationalist reasons, even though I am sure that not all of them are like that — am I racist?
Or if I own a hotel/restaurant and repeatedly encounter theft / leaving without paying מצד Jews / Arabs / Blacks / Swedes, and I decide not to give them service or to require them to pay before receiving the dish, again even though I know that not all of them are like that — I just want to protect my wallet. Is there a problem of racism here? Of course morally, not legally.
If in these cases there is racism (according to the definition I quoted), I understand why (although I have a vague feeling that it isn't), but if in your opinion this is not racism, I would appreciate an explanation.