1) the method of tree ring dating gave the following years A.D. for excavation site. Assume the population of x values has an approximately normal distribution. 1215, 1285, 1222, 1271, 1268, 1317, 1275 A) use the calculator with mean and standard deviation keys to find the sample mean year x and sample standard deviation s (round your answer to four decimal places) X=______ A.D. s= _______ yr B) find a 90% confidence interval for the meal of all tree ring dates from this archaeological site. (Round your answers to the nearest whole number) Lower limit _____ A.D. Upper limit ______ A.D. 2)Assume the population of x values has an approximately normal distribution 1278, 1250, 1313, 1208, 1268, 1316, 1275, 1317,1275 A) use a calculator with mean and standard deviation keys to find the sample mean year x and sample standard deviation s (round your answer to four decimal places) x=______ A.D. s= _______ yr B) when finding a 90% confidence interval, what is the critical value for the confidence level (give your answer to three decimal places) Tc =______ What is the maximal margin of error when finding 90% confidence interval for the mean of all tree ring dates from this archaeological site? (Round your answer to nearest whole number) e= ______ Find a 90 % confidence interval for the mean of all tree ring dates from this archaeological site. (Round your answer to the nearest whole number) Lower limit ______ A.D. Upper limit _______ A.D 3)assume the population of x values has an approximately normal distribution 1250, 1201, 1313, 1320, 1268, 1316, 1275, 1317, 1275 A) use a calculator with mean and standard deviation keys to find the sample mean year x and sample standard deviation (round your answer to four decimal places) X=_______ A.D. S= ________ yr B) find 90 % confidence interval for the mean of all tree ring dates from this archaeological site. (Round your answers to the nearest whole number). Lower limit ____ A.D. Upper limit ______ A.D