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. 1,257 1,180 1,208 1,299 1,268 1,316 1,275 1,317 1,275 LA USE SALT (2] Use a calculator with mean and standard deviation keys to find the sample mean year & and sample standard deviation s. (Round your answers four decimal places.) A.D. (b) Find 3 90%% confidence Interval for the mean of all tree ring dates from this archaeological site. (Round your answers to the nearest whole numb lower limit AD. upper limit A.D