12) (11 pts) A social worker wishes to know whether the mean annual income of her clients matches the mean annual income for all city residents which is $28000. She obtains a random sample of her clients of size 36. The mean of the sample is $27500 and the standard deviation of the sample is $1200. a) Identify Ho and Ha using math symbols. (2) Ho Ha b) Find the critical region for the hypothesis test, assuming the Level of Confidence is 90% (3) c) Calculate the test statistic. (2) d) State the decision and conclusion regarding the Null Hypothesis if a = 0.05. (4)