Order of learning mathematics for test design/test analyst?

Question

Software testing

Given:
Combinatorics
Mathematical statistics
Probability theory
Question:
In what order should these sections of mathematics be considered in order to facilitate the process of "entering" understanding as much as possible?
Maybe something was missed?
PS: The study of the material is not for a dissertation and not for a doctorate, but for the development of a look at testing.
Maybe there are people who took programs in universities in a certain order. (Maybe that's what I really wanted to know)

Answer 1

We had
Combinatorics then in parallel Statistics and Probability Theory Combinatorics -> Probability Theory (since it uses combinatorics) -> Statistics (since it uses both of the previous ones)
will be consistently correct