(a) Enter the following data into R, then find a 90% confidence interval for the mean, assuming a Normal distribution with (i) unknown population standard deviation o, and (ii) known population standard deviation = 5. 8.1, 15.3, 14.0, 7.0, 9.3, 19.1, 13.0, 18.0, 13.9, 12.4, 14.7