Thank you for all the comments.
That is true that the measurement has lots of noises, roughly about 20% of the average level. For next step approximation (extrapolation), I do not want to find an exact number and just best possible approximation with a smaller error can be OK. Unfortunately the...
I would like to extrapolate the results of a measurement. Following picture shows the measurements results. The best I can do is that to calculate the average values for 10 measurement and I use it for approximation, but the error is too large. In the following figure the blue graph is for...