The Manager of a Fast Food Restaurant Wants to Determine

The manager of a fast food restaurant wants to determine how sales in a given week are related to the number of discount vouchers (#) printed in the local newspaper during the week. The number of vouchers and sales ($000s) from 10 randomly selected weeks is given below with the predicted sales.
Calculate the residuals. $$\begin{array} { | c | c | c | } \hline \text { observation } & \text { Sales } & \text { predicted Sales } \\\hline 1 & 12.8 & 13.4147 \\\hline 2 & 15.4 & 14.8000 \\\hline 3 & 13.9 & 13.8765 \\\hline 4 & 11.2 & 12.9529 \\\hline 5 & 18.7 & 20.3412 \\\hline 6 & 17.9 & 16.1853 \\\hline 7 & 16.8 & 15.2618 \\\hline 8 & 15.9 & 14.3382 \\\hline 9 & 11.5 & 12.9529 \\\hline 10 & 13.9 & 13.8765 \\\hline\end{array}$$