Each year, the American Federation of Teachers (AFT) reports the state-by-state average salary for teachers in public

Question:

Each year, the American Federation of Teachers (AFT) reports the state-by-state average salary for teachers in public schools. In a recent study, the AFT reported an average salary of $60,583 for teachers in California, ranking the state sixth in the country. If this California average was based on a sample of 200 randomly selected teachers,
a. Construct a 95% confidence interval estimate of the mean salary for the population of California public school teachers. Assume that the population standard deviation is $6800.
b. Construct the 99% interval.