As part of a study of residential property values in Cedar Grove, New Jersey, the county tax assessor sampled 20 single-family homes that sold during 1996 and recorded their sales prices (in thousands of dollars; see table below). A stem-and-leaf display and descriptive statistics for these data are shown in the MINITAB printout on p. 295.

a. On the MINITAB printout, locate a 95% confidence interval for the mean sale price of all singlefamily homes in Cedar Grove, New Jersey.

b. Give a practical interpretation of the interval, part a.

c. What is meant by the phrase "95% confidence" as it is used in this exercise?

d. Comment on the validity of any assumptions required to properly apply the estimation procedure.