The article “Frost Belt Feels Labor Drain” (USA Today, May 1, 2008) points out that even though total population is increasing, the pool of young workers is shrinking in many states. This observation was prompted by the data in the accompanying table. Entries in the table are the percent change in the population of 25- to 44-year-olds over the period from 2000 to 2007. A negative percent change corresponds to a state that had fewer 25- to 44-year-olds in 2007 than in 2000 (a decrease in the pool of young workers).
a. The smallest value in the data set is _11.9 and the largest value is 22.0. One possible choice of stems for a stem-and-leaf display would be to use the tens digit, resulting in stems of -1, - 0, 0, 1, and 2. Notice that because there are both negative and positive values in the data set, we would want to use two 0 stems—one where we can enter leaves for the negative percent changes that are between 0 and - 9.9, and one where we could enter leaves for the positive percent changes that are between 0 and 9.9. Construct a stem-and-leaf plot using these five stems. (Hint: Think of each data value as having two digits before the decimal place, so 4.1 would be regarded as 04.1.)
b. Using two-digit stems would result in more than 30 stems, which is more than we would usually want for a stem-and-leaf display. Describe a strategy for using repeated stems that would result in a stemand- leaf display with about 10 stems.
c. The article described “the frost belt” as the cold part of the country—the Northeast and Midwest— noting that states in the Frost Belt generally showed a decline in the number of people in the 25- to 44-year-old age group. How would you describe the group of states that saw a marked increase in the number of 25- to 44-year-olds?

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