The dickhead math goblin that lives in my brain wants to point out that's not how averages work.
The average is 5.17 inches. You get an average by adding all the numbers together then dividing by how many numbers there are. Standards have nothing to do with it, it's basically just a way of finding the middle number on a list.
Little maths joke - 50% of people have an above average number of legs. Absolutely true.