3.17 ● The article “Going Wireless” (AARP Bulletin, June 2009)

reported the estimated percentage of households with only wireless phone service (no land line) for the 50 U.S. states and the District of Columbia. In the accompanying data table, each state was also classified into one of three geographical regions—West (W), Middle states (M), and East (E).

Wireless

% Region State Wireless

% Region State 13.9 M AL 9.2 W MT 11.7 W AK 23.2 M NE 18.9 W AZ 10.8 W NV 22.6 M AR 16.9 M ND 9.0 W CA 11.6 E NH 16.7 W CO 8.0 E NJ 5.6 E CN 21.1 W NM 5.7 E DE 11.4 E NY 20.0 E DC 16.3 E NC 16.8 E FL 14.0 E OH 16.5 E GA 23.2 M OK 8.0 W HI 17.7 W OR 22.1 W ID 10.8 E PA 16.5 M IL 7.9 E RI 13.8 M IN 20.6 E SC 22.2 M IA 6.4 M SD 16.8 M KA 20.3 M TN 21.4 M KY 20.9 M TX 15.0 M LA 25.5 W UT 13.4 E ME 10.8 E VA 10.8 E MD 5.1 E VT 9.3 E MA 16.3 W WA 16.3 M MI 11.6 E WV 17.4 M MN 15.2 M WI 19.1 M MS 11.4 W WY 9.9 M MO

a. Construct a stem-and-leaf display for the wireless percentage using the data from all 50 states and the District of Columbia. What is a typical value for this data set?

b. Construct a back-to-back stem-and-leaf display for the wireless percentage of the states in the West and the states in the East. How do the distributions of wireless percentages compare for states in the East and states in the West? (Hint: See Example 3.11.)