In October, the Campus Bookstore Asked a Random Set of Freshmen

Multiple Choice

In October, the campus bookstore asked a random set of freshmen and seniors how much they had spent on textbooks that semester. The bookstore believes that the two groups spent the same amount. What is an appropriate test value for a $z$ test?
$\begin{array}{lcc}\hline & \text { Freshmen } & \text { Seniors } \\\hline \text { Sample size } & 80 & 70 \\\text { Sample mean } & \$ 460 & \$ 440 \\\text { Population std. dev. } & \$ 52 & \$ 63 \\\hline\end{array}$

A) 9.51
B) 1.21
C) 0.22
D) 2.10