# 7 suppose we fit a least squares regression line to a

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7.Suppose we fit a least-squares regression line to a set of data.What is true if a plot of theresiduals shows a curved pattern?(a) A straight line is not a good model for the data.(b) The correlation must be 0.(c) The correlation must be positive.(d) Outliers must be present.(e) The regression line might or might not be a good model for the data, depending on theextent of the curve.
8.Mr. Nerdly asked the students in his AP Statistics class to report their overall grade pointaverages and their SAT Math scores.The scatterplot below provides information about hisstudents’ data.The dark line is the least-squares regression line for the data, and its equationisˆ410.5467.3yx²Which of the following statements about the circled point is false?4.03.53.02.5700650600550GPASAT Math scoreSAT Math versus GPA.
Are jet skis (otherwise known as personal watercraft, or PWC) dangerous?An article in theAugust 1997 issue of theJournal of the American Medical Associationreported on a survey thattracked emergency room visits at randomly selected hospitals nationwide.The study recordeddata on the number of jet skis in use and the number of accidents related to their use for the years19901995.Computer output and a residual plot from a linear regression of jet-ski relatedinjuriesversusjet skis in use (PWC) are shown below.Questions 9 and 10 refer to these data.9.The circled point represents a year when thenumber of PWC in use was 240,000.Thenumber of observed injuries in that year wasclosest to:150010005000ResidualResiduals Versus PWC(response is injuries)PredictorCoefSE CoefConstant-27451372-2.000.116PWC0.0180780.0028056.440.003S = 1218.65R-Sq = 91.2%R-Sq(adj) = 89.0%800000700000600000500000400000300000200000-500-1000PWCTP
10.Which of the following best describes what s = 1218.65 represents in this setting?
134The Practice of Statistics, 4/e- Chapter 3© 2011 BFW Publishers
© 2011 BFW PublishersThe Practice of Statistics, 4/e- Chapter 3135Part 2:Free ResponseShow all your work.Indicate clearly the methods you use, because you will be graded on thecorrectness of your methods as well as on the accuracy and completeness of your results andexplanations.

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