ODD ANSWERS A85 25. 83.332 6 y 6 111.788 You can be 99% confident that the mean annual wage will be between $83,332 and $111,788 when the percentage of employment in STEM occupations is 13% in the industry. 27. 1714.764 6 y 6 4402.104 You can be 95% confident that the export of natural gas from the United States will be between 1,714,764,000,000 and 4,402,104,000,000 cubic feet when the production of natural gas in the United States is 31 trillion cubic feet. 29. 2060.436 6 y 6 3015.384 You can be 95% confident that the new vehicle sales of General Motors will be between 2,060,436 and 3,015,384 when the new vehicle sales of Ford are 2,028,000. 31. x Year Average age (in years) y 2013 2015 2017 2019 2021 11.3 11.4 11.5 11.6 11.7 11.8 11.9 12.0 12.1 12.2 33. 0.960. About 96.0% of the variation in the average age of vehicles can be explained by the relationship between the year and the average age of vehicles and about 4% of the variation is unexplained. 35. Fail to reject H0. There is not enough evidence at the 1% level of significance to support the claim that there is a linear relationship between weight and number of hours slept. 37. -199.553 6 B 6 288.879; 102.795 6 M6 272.526 Section 9.4 (page 512) 1. The predicted y-value, ny, will change by -8.2 when the variable x2 is changed by one unit and x1 and x3 are held constant. 3. (a) 18,832.7 pounds per acre (b) 18,016.4 pounds per acre (c) 17,350.6 pounds per acre (d) 16,190.3 pounds per acre 5. (a) 7.5 cubic feet (b) 16.8 cubic feet (c) 51.9 cubic feet (d) 62.1 cubic feet 7. (a) ny = 27,641.224 - 1597.534x 1 - 80.171x2 (b) 1915.046 (c) 0.860 The standard error of estimate of the predicted price given specific age and mileage of pre-owned Honda Civic sedans is about $1915.05. The multiple regression model explains about 86.0% of the variation. 9. 0.838 Uses and Abuses for Chapter 9 (page 514) 1 – 2. Answers will vary. Review Exercises for Chapter 9 (page 516) 1. (a) x Pass attempts Passing yards y 350 450 550 650 2500 3000 3500 4000 4500 5000 (b) 0.937 (c) Strong positive linear correlation. As the number of pass attempts increase, the number of passing yards tends to increase. 3. (a) x IQ score Brain sizes (in grams) y 65 85 105 125 1100 1200 1300 1400 1500 1600 1700 1800 (b) -0.068 (c) No linear correlation. The IQ does not appear to be related to brain size. 5. There is enough evidence at the 5% level of significance to conclude that there is a significant linear correlation between a quarterback’s pass attempts and passing yards. 7. There is not enough evidence at the 1% level of significance to conclude that there is a significant linear correlation between the IQ scores and brain sizes. 9. ny = 0.097x - 695.161 x Milk cows (in thousands) Milk produced (in billions of pounds) y 9200 9300 9400 9500 200 204 208 212 216 220 224 (a) It is not meaningful to predict the value of y for x = 9080 because x = 9080 is outside the range of the original data. (b) 202.806 billions of pounds (c) 213.507 billions of pounds (d) 219.345 billions of pounds
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