Chapter 8 Part I Answers The explanatory variable (x) is initial drop, measured in feet, and the response variable (y) is duration, measured in seconds.
Chapter 8 Part I Answers The units of the slope are seconds per foot.
Chapter 8 Part I Answers The slope of the regression line predicting duration from initial drop should be positive. Coasters with higher initial drops probably provide longer rides.
Chapter 8 Part I Answers 12.4% of the variability in duration can be explained by variability in initial drop. (In other words, 12.4% of the variability in duration can be explained by the linear model.)
Chapter 8 Part I Answers a) +9 +9
Chapter 8 Part I Answers b)
Chapter 8 Part I Answers c)
Chapter 8 Part I Answers d)
Chapter 8 Part I Answers The curved pattern in the residuals plot indicates that the linear model is not appropriate. The relationship is not linear.
Chapter 8 Part I Answers
The scattered residuals plot indicates an appropriate linear model.
Chapter 8 Part I Answers
The duration of a coaster whose initial drop is one standard deviation below the mean drop would be predicted to be about standard deviations (in other words, r standard deviations) below the mean duration.
Chapter 8 Part I Answers The duration of a coaster whose initial drop is three standard deviations above the mean drop would be predicted to be about (or 3x0.352) standard deviations above the mean duration.
Chapter 8 Part I Answers According to the linear model, the duration of a coaster ride is expected to increase by about seconds for each additional foot of initial drop.
Chapter 8 Part I Answers According to the linear model, a coaster with a 200 foot initial drop is expected to last seconds.
Chapter 8 Part I Answers According to the linear model, a coaster with a 150 foot initial drop is expected to last seconds. i. The advertised duration is shorter, at 120 seconds. 120 – = So, seconds less than predicted. ii. This is a negative residual (over estimate)