So, been up all night working on getting the velocity/angle of arrow simulations perfect. Running into an issue with the physics engine I'm using is ever so slightly off (probably a rounding issue)
The Velocity is a fixed 55 "Units"
Correction Required at ranges (Range being the variable):
Range | Correction
30 0.0180
100 0.0055
200 0.0027
300 0.00165
After applying manual corrections on the velocity, I've been able to come up with the above data set.
Would anyone be so kind as to help me figure out a formula which satisfies the above problem?
Minor Background Information
The formulas I am using for the base calculations are https://en.wikipedia.org/wiki/Trajectory_of_a_projectile
Inspired by Frentos's answer, for the time being, let us assume something like $$y=\frac ax+b$$ Using your values, a simple linear regression gives $$y=\frac{0.541976}{x}-0.000038024$$ which gives as predicted corrections $0.01803$, $0.00538$, $0.00267$, $0.00177$.
As said, with more data points, something better could come out.
Edit
Take care; the constant term is not significant. So, $y=\frac{0.540401}{x}$ seems to more than sufficient (predicted values $0.01801$, $0.00540$, $0.00270$, $0.00180$)