Note for hypothesis tests:
You must show: the null and alternative, the p-value or test statistic, the rejection region or inequality
used to make the decision, the decision, the interpretation IN TERMS OF THE GIVEN SITUATION. Use a
significance level of 5% in all problems. You may use either the p-value method or the rejection region
method. This is up to you.
9. For years, a large discount store has used independent lines to check out customers. Historically,
the standard deviation of waiting times is 10 minutes. The manager tried a new, single-line
procedure. A random sample of 32 customers using this method had a standard deviation of 9.5
minutes in waiting time. Assuming waiting times are normal, test the claim that the st dev of the
waiting times are reduced by the new procedure using a significance level of 5%.