APPENDIX D 771 7. There does appear to be a linear correlation between the amounts of tar and the amounts of nicotine in cigarettes. 9. With n = 10 pairs of data, the critical values are {0.632. Because r = -0.475 is between -0.632 and 0.632, there is not sufficient evidence to conclude that there is a linear correlation. 11. With n = 9 pairs of data, the critical values are {0.666. Because r = 0.971 is in the right tail region beyond 0.666, there is sufficient evidence to conclude that there is a linear correlation. 13. Because the P-value is 0.166, which is not small (such as 0.05 or less), there is a high chance (16.6%) of getting the sample results when there is no correlation, so there is not sufficient evidence to conclude that there is linear correlation. 15. Because the P-value of 0.000 is small (such as 0.05 or less), there is a small chance of getting the sample results when there is no correlation, so there is sufficient evidence to conclude that there is a linear correlation. Chapter 2: Quick Quiz 1. Class width: 20. It is not possible to identify the original data values. 2. Class limits: 0 and 19. Class boundaries: -0.5 and 19.5. 3. 69 15. The distribution does not have much skewness. 17. Because the vertical scale starts with a frequency of 200 instead of 0, the difference between the “no” and “yes” responses is greatly exaggerated. The graph makes it appear that about five times as many respondents said “no,” when the ratio is actually a little less than 2.5 to 1. 19. The two costs are one-dimensional in nature, but the baby bottles are three-dimensional objects. The $4500 cost isn’t even twice the $2600 cost, but the baby bottles make it appear that the larger cost is about five times the smaller cost. 21. Section 2-4 1. The term linear refers to a straight line, and r measures how well a scatterplot of the sample paired data fits a straight-line pattern. 3. A scatterplot is a graph of paired 1x, y2 quantitative data. It helps us by providing a visual image of the data plotted as points, and such an image is helpful in enabling us to see patterns in the data and to recognize that there may be a correlation between the two variables. 5. There does not appear to be a correlation. The given data suggest that five-day predicted high temperatures are not very accurate. 4. Annual Tornadoes in Oklahoma Relative Frequency 0–19 4.3% 20–39 26.1% 40–59 30.4% 60–79 21.7% 80–99 8.7% 100–119 7.2% 120–139 0.0% 140–159 1.4% 5. 30, 30, 30, 31, 34, 34, 36, 36, 39 6. Pareto chart 7. Scatterplot 8. No, the term “normal distribution” has a different meaning than the term “normal” that is used in ordinary speech. A normal distribution has a bell shape, but the randomly selected lottery digits will have a uniform or flat shape. 9. Variation 10. Parts a, d, e describe normally distributed data.
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