The Bureau of Labor Statistics reported that the average yearly income of dentists in the year 2018 was $110,000. A sample of 81 dentists, which was taken in 2019, showed an average yearly income of $120,000. Assume the standard deviation of the population of dentists in 2019 is $36,000. We want to test to determine if there has been a significant difference in the average yearly income of dentists.

Following the steps for hypothesis testing, conduct this hypothesis test at the 5% level of significance.