In: Statistics and Probability
The mean income per year of employees who produce internal and external newsletters and magazines for corporations was reported to be $75500. These editors and designers work on corporate publications but not on marketing materials. As a result of poor economic conditions and oversupply, these corporate communications workers may be experiencing a decrease in salary. A random sample of 40 corporate communications workers revealed that x̄ = $72500. Conduct a hypothesis test to determine whether there is any evidence to suggest that the mean income per year of corporate communications workers has decreased. Assume that the population standard deviation is $6360. Please use the exact value (from R) for all critical values.
a)Calculate the appropriate 99% bound(z distribution). You do not need to have any decimal places in the answer; that is, the answer should be an integer
b) why hypothesis test at a 1% significance level and the a) result state the same thing?