Question #$7.$ Consider the following data set:

$\{\begin{array}{c}\text{:}Y=\left[\begin{array}{cccccc}5& 2& 0& 6& 10& 15\end{array}\right]\text{;}\end{array}$

a$)$ Create a third order best fit line for the provided data. Use the provided formulas to calculate the required coefficients.

b$)$ Solve for the third order coefficients using polyfit and compare your results to the ones from parta.

c$)$ Calculate the $r^2$ value for the created best fit equation.