You do NOT need to add your own score x. 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 >.

It does not matter. You could add your own points 1000 times and still pass the test (as long as you don't run into any rounding errors).