# Math

posted by
**Kris** on
.

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. The researcher phones a simple

random sample of 12 cell phone subscribers and obtains the monthly bills

94.25 38.94 79.15 56.78

70.07 115.59 77.56 37.01

55.00 76.05 27.29 52.48

Assuming SD=$18.49 and normal curve shape for the 2004 distribution of bills price, use the sample data to

determine whether the mean monthly cell phone bills is different from $50.64 at the p=0.05 level of

significance.