TABLE 13-4
the Managers of a Brokerage Firm Are Interested

TABLE 13-4
The managers of a brokerage firm are interested in finding out if the number of new clients a broker brings into the firm affects the sales generated by the broker. They sample 12 brokers and determine the number of new clients they have enrolled in the last year and their sales amounts in thousands of dollars. These data are presented in the table that follows. $\begin{array}{cccc}\underline {\text { Broker } } & \underline {\text { Clients } }& \underline {\text { Sales }} \\1 & 27 & 52 \\2 & 11 & 37 \\3 & 42 & 64 \\4 & 33 & 55 \\5 & 15 & 29 \\6 & 15 & 34 \\7 & 25 & 58 \\8 & 36 & 59 \\9 & 28 & 44 \\10 & 30 & 48 \\11 & 17 & 31 \\12 & 22 & 38\end{array}$
-Referring to Table 13-4, the managers of the brokerage firm wanted to test the hypothesis that the population slope was equal to 0. The denominator of the test statistic is $S_{b_{1}}$ . The value of $S_{b_{1}}$
in this sample is ________.