13. [0/4 Points] DETAILS PREVIOUS ANSWERS BBUNDERSTAT12 7.2.013.5. The method of tree ring dating gave the following years A.D. for an archaeological excavation site. Assume that the population of x values has an approximately normal distribution. 1,271 1,250 1,229 1,194 1,268 1,316 1,275 1,317 1,275 LA USE SALT (=) Use a calculator with mean and standard deviation keys to find the sample mean year x and sample standard deviation s. (Round your answers to four decimal places.) x = 12175 X A.D. 5 = 34 X yr (b) Find a 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 1256 X A.D. upper limit 1283 X A.D. Need Help? Rand It Which It