Nine Students Took the SAT Test $$\alpha$$ = 005 A)4
B)-4
C)41
D)-41

Nine students took the SAT test. Their scores are listed below. Later on, they took a test preparation course and retook the SAT. Their new scores are listed below. Use the Wilcoxon signed-rank test to find the test statistic
Ws to test the claim that the test preparation had no effect on their scores. Use $$\alpha$$ = 0.05. $$\begin{array} { l c c c c c c c c c } \hline \text { Student } & 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 & 9 \\\hline \text { Before Score } &820 & 920 & 810 & 1180 & 1060 & 1100 & 990 & 850 & 1150 \\\text { After Score } & 840 & 920 & 800 & 1220 & 1090 & 1110 & 980 & 890 & 1170\end{array}$$

A) 4
B) -4
C) 41
D) -41