### Estimating the Mean - Hypothesis Test

If 45 officials in student services earned an average of x(with a line over it) = $50,340 each year: a. Assume that the standard deviation is 16,920 for salaries of officials. Find the 90% confidence interval for the population mean salary of such personal. What is the margin of error. b. If SD is 10,780, Find the 90% conf