In a random sample of 12 adults from the U.S., the mean waste recycled per person per day was 1.4 pounds with a sample standard deviation of .3 pounds. Assume that the distribution of x = waste recycled per person per day is normal
(a) Construct a 95% confidence interval for the population mean.
(b) Instead of using the sample standard deviation, suppose you have historical data which indicates that the population standard deviation is .25 pounds. Construct a 95% confidence interval using this new information.
(c) Would your answer change if you did not know that the distribution of x = waste recycled per person per day is normal?