A particular brand of diet margarine was analyzed to determine the level of polyunsaturated fatty acid. A sample of six packages resulted in the following percentage values: 16.8, 17.2, 17.4, 16.9, 16.5, 17.1

a. Check the assumption that the level of polyunsaturated fatty acid is normally distributed.
b. Calculate a 99% confidence interval on the mean μ. Provide a practical interpretation of this interval.
c. Calculate a 99% lower confidence bound on the mean Compare this bound with the lower bound of the two-sided confidence interval and discuss why they are different.