Given any number (including decimals) between 12.5 and 87.5 I need to calculate another number based on these results:
Input = 12.5 | 31.25 | 50 | 68.75 | 87.5
Result = 12.5 | 64.5 | 78 | 84 | 87.5
So, for example, if "input = 25" or "input = 58", what can I use to calculate a result?
The only thing I can determine from looking at these numbers is that the closer the input is to 87.5, the smaller the increment in the result. (The result of 12.5 to 13.5 would have a much greater difference than 86.5 to 87.5).
You are looking for an interpolation function or a fitted curve that comes close to the points. It is a huge field in numerical analysis, and routines can be found in any text. If you plot the data in Excel, "Add Trendline", and "Show Equation on Graph" you can see the function and how well it fits. You can choose various functional forms to see what fits your needs.