Construct a 95% confidence interval for the population mean, . Assume the population has a normal distribution. A sample of 20 part-time workers had mean annual earnings of $3120 with a standard deviation of $677. Round to the nearest dollar.

Construct a 95% confidence interval for the population standard deviation of a random sample of 15 crates which have a mean weight of 165.2 pounds and a standard deviation of 12.2 pounds. Assume the population is normally distributed.