What does it mean to interpolate a data?
Using a best-fit line to estimate the value of one thing given the value of another.
Say you had a scatter graph and the values had a fairly good linear shape with little scattering, you could estimate (or given the data and a means of calculating, work it out) what the best-fit line. The best-fit line is the linear line which shows the relationship between two sets of data while reducing the amount of scattering on the graph.
Most likely, the best-fit line will have values on either side that will be slightly off the line, and we may not have data for one value.
For example, say a best-fit line followed the equation
So, say we had values of
We only use interpolation to estimate values within a range of data because extreme values, like