During the winter of2008-2009, the average utility bill for residents of a certain state was $180per month. A random sample of40customers was selected during the winter of2009-2010, and the average bill was found to be $170.18with a sample standard deviation of $20.68. Complete parts a and b below.

a)Using=0.05, does this sample provide enough evidence to conclude that the average utility bill in this state was lower in the winter of2009-2010 than it was in the winder of2008-2009?

Determine the hypotheses.

A.H0:180 and H1:>180

B.H0:=180 and H1:180

C.H0:180 and H1:=180

D.H0:180 and H1:<180

Determine the criticalvalue(s).

The criticalvalue(s) is(are)

Determine the teststatistic,tx.

What conclusion should bedrawn?