An insurance company stated that in 1987, the average yearly car insurance cost for a family in the U.S. was $1188. In the same year, a random sample of 37 families in California resulted in a mean cost of $1228 with a standard deviation of $21.00. Does this suggest that the average insurance cost for a family in California in 1987 exceeded the stated national average?
a. State the appropriate hypotheses for this question.
b. Test your hypotheses at a significance level of 5%. Interpret your results.