A population is known to be normally distributed. 1. Assuming that the population standard deviation is 2.8, compute the 95% confidence interval of the mean based on the following sample of nine: 8,9,10,13,14,16,17,20,21. 2. Now compute the 99% confidence interval using the same data, assuming that the population standard deviation is unknown.

Only R should be used for any plots or calculations.