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40 Chapter 1 %u2022 Analyzing One-Variable Data You can use the One Quantitative Variable, Multiple Groups applet at stapplet.com to make back-to-back stemplots for comparing the distribution of a quantitative variable in two groups. SOLUTION: (a) Atlantic Coast California8886421111150664088115115901060699864345678910111213141516171230 4KEY: 5 | 9 is a Californiaoak species with acornvolume 5.9 cm3. (b) California oak tree species tend to have larger acorn volumes ( median 4.1cm3 = ) than Atlantic Coast oak tree species ( median 1= .7 cm3). (c) The shapes of the distributions of acorn size in the two regions are quite different. For Atlantic Coast oak tree species, the distribution is skewed to the right and single-peaked. For%u00a0 California oak tree species, the distribution is also skewed to the right but has two distinct clusters (0.4 to 2.6cm3 and 4.1 to 7.1cm3 ), a large gap%u00a0from 7.1cm3 to 17.1cm3, and no clear peak. FOR PRACTICE TRY EXERCISE 15. 1. Make stems. The acorn volumes vary from 0.3 cm3 to 17.1cm3 . Use the whole-number part of each value as the stem and the decimal part as the leaf. So we need stems from 0 to 17. 2. Add leaves. 3. Order leaves. For each species, make sure the leaves increase in order going out from the stem. 4. Add a key.Remember: Skewed to the right means that the long tail is in the direction of the larger values. YO U R TU R N LE SSO N 1.4 Who wears seat belts? Each year, the National Highway Traffic Safety Administration (NHTSA) conducts an observational study of seat belt use in all 50 states. Trained observers station themselves at randomly selected locations along roadways in each state, and then record data on seat belt use by people in passing vehicles. The stemplot shows the percentage of observed people who were wearing seat belts in each state during a recent year. 40 vitapix/Getty Images%u00a9 Bedford, Freeman & Worth Publishers. For review purposes only. Do not distribute.