1. Assume random samples from normal populations with known variance (or standard deviation) were drawn. Find confidence intervals for the true population mean given the sample mean, population variance/standard deviation, and the confidence/alpha level.

a. N = 28, M = 14, 2 = 6, confidence level = 95%

b. N = 65, M= 190, =12, = 0.01

2. Now, suppose the population variance is not known, and the variance/standard deviation values given in the previous question are actually sample statistics. Find the confidence intervals using the t-distribution.

3. How do the results from question 2 compare to the results from question 1? (Respond in the form of a sentence.)