12. At Burnt Mesa Pueblo, the method of tree-ring dating gave the following years A.D. for an archeological excavation site (Bandelier Archaeological Excavation Project: Summer 1990 Excavations at Burnt Mesa Pueblo, edited by Kohler, Washington State University): 1189 1271 1267 1272 1268 1316 1275 1317 1275 Assume the population follows a normal distribution. a. Verify that the sample mean x ~ 1272 with a standard deviation s ~ 37 years. b. Find a 90% confidence interval for the mean of all tree-ring dates from this archaeological site. Round the lower and upper bounds to the nearest year. c. Explain the meaning of the confidence interval. 13. A sample of 8 items has an average fat content of 18.6 grams and a standard deviation of 2.4 grams. Assuming a normal distribution, construct a 99 percent confidence interval for H