use the Sample Size Estimator
In the early years of the twenty-first century, annual salaries for federal employees in the Upper Midwest averaged approximately $42,000, with a population standard deviation (?) of $4,900. If we drew a random sample of 25 federal employees from this population:
What would the standard error of the mean be?
What is the probability that the sample mean would be between $41,000 and $43,000?
What is the probability that the sample mean would be between $41,000 and $43,000 if we increased the sample size to 100?