You do NOT need to add your own score x (but you MAY, as written in the description). Proof :
The mean of the classroom (without your own score x) is : m1=(x1+x2+...+xn)/n.
The mean of the classroom (includind your own score x) is : m2=(x1+x2+...+xn+x)/(n+1)=(nm1+x)/(n+1).
If you know that m1<x then you know that m2<(nx+x)/(n+1) i.e m2<(n+1)x/(n+1) and finally m2<x. Same proof for >.

whats cheatin about it

Because they know basic math. 😉

The difference between the ruby way (commented out) and Gauss' method is the runtime and memory usage. Gauss' takes constant time and memory, where the series takes linear time to build.

If you somewhy needed a high performance version Gauss's is better, but for readability and maintainability I do agree the commented version is very clear.

The results are the same! Aren't they?

It doesn't change the situation. Suppose your point is larger than the average.Adding your point increases the average but still smaller than your point.

The tests will always use some integral number, so don't worry about that in dynamic typed languages.

If the tests don't use numbers, the kata translator hasn't paid attention.

great kata, it f**ked my mind

what about if X isn't a number?

What?

Round 6 - Fight...!?!?!?!!! :)

ok, here we go

Can we close the issue and possibly move on, so that I can approve the kata?

mistake in Ruby test (method name)

strange kata. How high is creator?

backdoor