3.25 ● The data in the accompanying table represents the percentage of workers who are members of a union for each U.S. state and the District of Columbia (AARP Bulletin, September 2009).

State % of Workers who Belong to a Union Alabama 9.8 Alaska 23.5 Arizona 8.8 Arkansas 5.9 California 18.4 Colorado 8.0 Connecticut 16.9 Delaware 12.2 District of Columbia 13.4 Florida 6.4 Georgia 3.7 State % of Workers who Belong to a Union Hawaii 24.3 Idaho 7.1 Illinois 16.6 Indiana 12.4 Iowa 10.6 Kansas 7.0 Kentucky 8.6 Louisiana 4.6 Maine 12.3 Maryland 15.7 Massachusetts 12.6 State % of Workers who Belong to a Union Michigan 18.8 Minnesota 16.1 Mississippi 5.3 Missouri 11.2 Montana 12.2 Nebraska 8.3 Nevada 16.7 New Hampshire 3.5 New Jersey 6.1 New Mexico 10.6 New York 18.3 North Carolina 7.2 North Dakota 24.9 Ohio 14.2 State % of Workers who Belong to a Union Oklahoma 6.6 Oregon 16.6 Pennsylvania 15.4 Rhode Island 16.5 South Carolina 3.9 South Dakota 5.0 Tennessee 5.5 Texas 4.5 Utah 5.8 Vermont 4.1 Virginia 10.4 Washington 19.8 West Virginia 13.8 Wisconsin 15.0 Wyoming 7.7

a. Construct a histogram of these data using class intervals of 0 to ,5, 5 to ,10, 10 to ,15, 15 to ,20, and 20 to ,25.

b. Construct a dotplot of these data. Comment on the interesting features of the plot. (Hint: Dotplots were covered in Section 1.4.)

c. For this data set, which is a more informative graphical display—the dotplot from Part

(b) or the histogram constructed in Part (a)? Explain.

d. Construct a histogram using about twice as many class intervals as the histogram in Part (a). Use 2.5 to ,5 as the first class interval. Write a few sentences that explain why this histogram does a better job of displaying this data set than does the histogram in Part (a).