A sample of 15 quality control managers with more than 20 years experience have an average salary of $68,000 and a sample standard deviation of $19,000.
a. You can be 95% confident that the mean salary for all quality managers with at least 20 years of experience is between what two numbers? What assumption are you making about the distribution of salaries?
b. What size sample is needed to ensure that you can estimate the population mean salary of all quality managers with more than 20 years of experience and have only one chance in 100 of being off by more than $500?