TABLE 13-10
the Management of a Chain Electronic Store Would

TABLE 13-10
The management of a chain electronic store would like to develop a model for predicting the weekly sales (in thousand of dollars) for individual stores based on the number of customers who made purchases. A random sample of 12 stores yields the following results:
$$\begin{array} { | l | l | } \hline \text { Customers } & \text { Sales (Thousands of Dollars) } \\\hline 907 & 11.20 \\\hline 926 & 11.05 \\\hline 713 & 8.21 \\\hline 741 & 9.21 \\\hline 780 & 9.42 \\\hline 898 & 10.08 \\\hline 510 & 6.73 \\\hline 529 & 7.02 \\\hline 460 & 6.12 \\\hline 872 & 9.52 \\\hline 650 & 7.53 \\\hline 603 & 7.25 \\\hline\end{array}$$
-Referring to Table 13-10, what are the degrees of freedom of the t test statistic when testing whether the number of customers who make purchase affects weekly sales?