According to the local union president, the mean gross income of the plumbers in the Salt Lake City area is normally distributes, with a mean $30,000 and a standard deviation of $2,600. A recent investigative reporter for a TV station found, for a sample of 77 plumbers, that the mean gross income was $30,500. At the 0.05 significance level can we conclude that the mean is greater than $30,000?
Find the test statistic and critical value. What would the Ho and Ha be? Would you reject or fail to reject the null hypothesis?