The standard deviation of a normally distributed population is equal to 10. A sample size of 25 is selected, and its mean is found to be 95.
a.) Find an 80% confidence interval for mu (the mean)
b.) If the sample size were 100 what would be the 80% confidence interval?
c.) If the sample size was 25 but the standard deviation was 5, what would be the 80% confidence interval?