During the winter of? 2008-2009, the average utility bill for residents of a certain state was ?$173 per month. A random sample of 30 customers was selected during the winter of? 2009-2010, and the average bill was found to be ?$163.41 with a sample standard deviation of ?$22.28.
?a) Using alpha α=0.05?, does this sample provide enough evidence to conclude that the average utility bill in this state was lower in the winter of? 2009-2010 than it was in the winder of? 2008-2009?
Determine the hypotheses.