The Following Are Monthly Sales (In Thousands of Dollars) of Two

Essay

The following are monthly sales (in thousands of dollars) of two department stores, A and B, for the months January through December 1979:
10 and 9,7 and 4,8 and 5, 7 and 6,11 and 10,15 and 16,
15 and 13,12 and 13,9 and 8,18 and 17,19 and 13,21 and 20.
-For the situation above, use the large sample sign test with $\alpha=0.05$ to test the null hypothesis that on the average the two department stores have equal sales against the alternative that on the average
a. department store $\mathrm{A}$ has more sales.
b. there is a difference in sales between the two stores.