According to CTIA-The wireless association, the mean monthly cell phone bill in 2004 was $50.64.A market researcher believes that the mean monthly cell phone bill is different today, but is not sure whether bills have declined because of technological advances or increased due to additional use. A random sample of 50 cell phone bills taken shows a mean charge of $52.35 and a standard deviation of $3.67. Test to see if the mean cell phone bill has changed since 2004. Use a .05 level of significance for the test.