Consumer Reports provided overall customer satisfaction scores for AT&T, Sprint, T-Mobile, and Verizon cell-phone services in major metropolitan areas throughout the United States. The rating for each service reflects the overall customer satisfaction considering a variety of factors such as cost, connectivity problems, dropped calls, static interference, and customer support. A satisfaction scale from 0 to 100 was used with 0 indicating completely dissatisfied and 100 indicating completely satisfied. The ratings for the four cell-phone services in 20 metropolitan areas are as shown (Consumer Reports, January 2009).

a. Consider T-Mobile first. What is the median rating?

b. Develop a five-number summary for the T-Mobile service.

c. Are there outliers for T-Mobile? Explain.

d. Repeat parts (b) and (c) for the other three cell-phone services.

e. Show the box plots for the four cell-phone services on one graph.

Discuss what a comparison of the box plots tells about the four services. Which service did Consumer Reports recommend as being best in terms of overall customer satisfaction?

Metropolitan Area AT&T Sprint T-MobileVerizon 71 70 Jacksonville 75 73 Minneapolis 71 San Antonio 73 73 71