Question 992280
These are three points for the relation:
(80,2.8),(90,3.0),(95,3.25).  The coordinates are  percent lean, price per pound.


Check the two neighboring slopes to find if the points fit a line.
{{{system((3-2.8)/10,0.25/5)}}},
{{{system(0.2/10,0.25/5)}}},
{{{system(1/50,1/20)}}}.
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The slopes are different, so a line will not be a fit.


You are free to pick another function shape to try to extrapolate what the price could be for 100% lean beef.  You can plot the points and try to judge visually if you like.  


Also notice that the slopes seem to be getting bigger as percent leanness increases.  I did not finish this; the question is at least a bit open-ended.