You generate a scatter plot using Excel. You then have Excel plot the trend line and report the equation and the $\displaystyle {r}^{{2}}$ value. The regression equation is reported as $\displaystyle {y}=-{89.09}{x}+{44.45}$ and the $\displaystyle {r}^{{2}}={0.8836}$.

What is the correlation coefficient for this data set?
r =