9.21 Based on population figures and other general information on the population, suppose it has been estimated that, on average, a family of four has about $1,135 annually in dental expenditures. Suppose further that a regional dental association wants to determine if this figure is accurate for its area of the country. To test this, 22 families of four are randomly selected from the population in that area of the country and a log is kept of the family's dental expenditures for one year. The resulting data are given below. Assuming that dental expenditures are normally distributed in the population, use the data and an = 0.05 to test the dental association's hypothesis.

1,008 812 1,117 1,323 1,308 1,415

831 1,021 1,287 851 930 730

699 872 913 944 954 987

1,695 995 1,003 994

1. Write down the hypotheses to be tested
2. Draw the figure
3. Do you reject or fail to reject the null hypothesis
4. At =0.05 what is the conclusion in relation to average family expenditure on dental