ODD ANSWERS A83 19. ny = 7.451x + 37.449 2 8 10 20 40 60 80 100 x Hours studying Test score y 4 6 (a) 60 (b) 86 (c) It is not meaningful to predict the value of y for x = 13 because x = 13 is outside the range of the original data. (d) 71 21. ny = -2.044x + 520.668 55 60 65 70 75 80 85 90 95 100 300 x y Heart rate (in beats per minute) QT interval (in milliseconds) 320 340 360 380 400 420 (a) It is not meaningful to predict the value of y for x = 120 because x = 120 is outside the range of the original data. (b) 384 milliseconds (c) 337 milliseconds (d) 351 milliseconds 23. ny = 2.979x + 52.476 x Calories Sodium (in milligrams) y 90 150 210 200 300 400 500 600 700 800 (a) 559 milligrams (b) 350 milligrams (c) It is not meaningful to predict the value of y for x = 260 because x = 260 is outside the range of the original data. (d) 678 milligrams 25. ny = 1.870x + 51.360 8 9 10111213 66 68 70 72 74 x Shoe size Height (in inches) y (a) 72.865 inches (b) 66.320 inches (c) It is not meaningful to predict the value of y for x = 15.5 because x = 15.5 is outside the range of the original data. (d) 70.060 inches 27. Strong positive linear correlation. As the years of experience of the registered nurses increase, their salaries tend to increase. 29. No, it is not meaningful to predict a salary for a registered nurse with 28 years of experience because x = 28 is outside the range of the original data. 31. (a) ny = -4.297x + 94.200 1 2 3 4 5 6 7 60 70 80 90 100 x Row 1 Row 2 y (b) ny = -0.141x + 14.763 60 70 80 90 100 1 2 3 4 5 6 7 x Row 2 Row 1 y (c) The slope of the line keeps the same sign, but the values of m and b change. 33. (a) ny = 0.139x + 21.024 (b) 30 40 50 60 32 28 30 26 22 24 x y (c) x 30 40 50 60 −2 −4 2 4 6 Residual (d) The residual plot shows a pattern because the residuals do not fluctuate about 0. This implies that the regression line is not a good representation of the relationship between the two variables.
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