The number of cell phone users has increased dramatically since 1987. According to the Semi-annual Wireless Survey, published by the Cellular Telecommunications & Internet Association, the mean local monthly bill for cell phone users in the United States was $49.94 in 2007. A hypothesis test is to be performed to determine whether last year’s mean local monthly bill for cell phone users has decreased from the 2007 mean of $49.94.
a. Determine the null hypothesis.
b. Determine the alternative hypothesis.
c. Classify the hypothesis test as two tailed, left tailed, or right tailed.