The bureau of labor statistics reported that the average yearly income of dentists in the year 2009 was $110,000. a sample of 81 dentists, which was taken in 2010, showed an average yearly income of $120,000. assume the standard deviation of the population of dentists in 2010 is $36,000. a. we want to test to determine if there has been a significant increase in the average yearly income of dentists. provide the null and the alternative hypothesis. b. compute the test statistic. c. determine the p -value; and at 95% confidence, test the hypothesis.