Julia is studying the satisfaction of customers in the selection of produce at grocery stores. She conducts interviews at the checkout and collects the results. What type of research is she conducting?

Least square fit to polynomial write a function leastsquarefit3pol that solves a linear system of equations to find a least squares fit of a third order polynomial to an experimental data set given as two row arrays. the function leastsquarefit3pol must explicitly solve a set of linear equations and cannot use polyfit. there should be no restriction on the size of the problem that can be solved.