You are correct. It is data dependent.
Using 3's and 5's, the average comes out to 4, DISTINCT or not. That's because the average is 4.xxx which comes out to 4 integer. Put in enough 3's, though, and it would come out as 3.xxx and report as a 3.
Change to some 7's, and the average is sometimes 5.xxx and sometimes 4.xxx, depending on how many of the numbers we use. (Use enough 7's, and it would be 6.xxx)
I didn't "test" enough data cases! - Still, it shows the problems that can crop up if you aren't paying attention to integer arithmetic.