The salaries of professional employees at a university show a mean salary of $59,593. Thirty employees were randomly selected professional employees at a branch campus were found to have a mean salary of $58,800 with a population standard deviation of $1,500. Based on a .01 level of significance can it be concluded that the branch campus employees earn less than main campus employees? Also, what is the Critical value?

Z= -3.21 and a CV= -1.96

z= -2.90 and a CV = -2.33

z= -1.87 and a CV = -1.65

z= -2.87 and a CV = -1.96