For each of the following sets of numbers, calculate a 95% confidence interval for the mean (σ not known);

before calculating the confidence interval, the sample mean (X) and standard deviation (s) must be calculated.

a. 3, 6, 4, 2, 5

b. 9, 13, 19, 6, 20, 15, 11

c. 59, 54, 61, 72, 50, 66, 48, 70, 53, 63