A research analyst disputes a trade group’s prediction that back-to-school spending will average $606.40 per family this year. She believes that average back-to-school spending will significantly differ from this amount. She decides to conduct a test on the basis of a random sample of 30 households with school-age children. She calculates the sample mean as $622.85. She also believes that back-to-school spending is normally distributed with a population standard deviation of $65.

a. Specify the competing hypotheses in order to test the research analyst’s claim.

b. Calculate the value of the test statistic.

c. Calculate the p -value and state the decision rule.

d. At the 5% significance level, does average back-to-school spending differ from

$606.40? P-56