3.19 The U.S. gasoline tax per gallon data for each of the 50 states and the District of Columbia were listed in the article “Paying at the Pump” (AARP Bulletin, June 2010).

State Gasoline tax*

Alabama 20.9 Alaska 8.0 Arizona 19.0 Arkansas 21.8 California 48.6 Colorado 22.0 Connecticut 42.6 Delaware 23.0 District of Columbia 23.5 Florida 34.4 Georgia 20.9 Hawaii 45.1 Idaho 25.0 Illinois 40.4 Indiana 34.8 Iowa 22.0 Kansas 25.0 Kentucky 22.5 Louisiana 20.0 Maine 31.0 Maryland 23.5 Massachusetts 23.5 State Gasoline tax*

Michigan 35.8 Minnesota 27.2 Mississippi 18.8 Missouri 17.3 Montana 27.8 Nebraska 27.7 Nevada 33.1 New Hampshire 19.6 New Jersey 14.5 New Mexico 18.8 New York 44.9 North Carolina 30.2 North Dakota 23.0 Ohio 28.0 Oklahoma 17.0 Oregon 25.0 Pennsylvania 32.3 Rhode Island 33.0 South Carolina 16.8 South Dakota 24.0 Tennessee 21.4 Texas 20.0 State Gasoline tax*
Utah 24.5 Vermont 24.7 Virginia 19.6 Washington 37.5 State Gasoline tax*
West Virginia 32.2 Wisconsin 32.9 Wyoming 14.0

a. Construct a stem-and-leaf display of these data.

b. Based on the stem-and-leaf display, what do you notice about the center and spread of the data distribution?

c. Do any values in the data set stand out as unusual? If so, which states correspond to the unusual observations, and how do these values differ from the rest?