# 13 what is the slope of the regression line interpret

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13.What is the slope of the regression line?Interpret the slope in the context of this problem.14.Explain what the quantity S = 3899.57 measures in the context of this problem.15.Below is the same scatterplot, but with the six intersections in California plotted as circlesand the four in other western states plotted as squares.Comment on how the relationship between average number of vehicles per day and hours ofdelay per year differs between the California intersections and the intersections in otherwestern states.32000030000028000026000024000022000020000028000260002400022000200001800016000140001200010000average vehicles per dayHours of delay per yearScatterplot of annual hours of delay vs vehicles per dayPredictorCoefSE CoefConstant-36297367-0.490.634vehicles per day0.078220.026842.910.017S = 3899.57R-Sq = 48.6%R-Sq(adj) = 42.8%TP
© 2011 BFW PublishersThe Practice of Statistics, 4/e- Chapter 3131An ecologist studying breeding habits of the common crossbill in different years finds that thereis a linear relationship between the number of breeding pairs of crossbills and the abundance ofthe spruce cones.Below are statistics on eight years of measurements, wherex= averagenumber of cones per tree andy= number of breeding pairs of crossbills in a certain forest.MeanStandard deviationx= mean number of cones/tree23.016.2y= number of crossbill pairs18.015.1The correlation betweenxandyisr= 0.96816.Find the equation of the least-squares regression line (withyas the response variable).17.What percentage of the variation in numbers of breeding pairs of crossbills can be accountedfor by this regression?18.Based on these data, can we conclude that the abundance of spruce cones is responsible forthe number of breeding pairs of crossbills?Explain.
Test 3CAP StatisticsName:Part 1:Multiple Choice.Circle the letter corresponding to the best answer.1.On May 11, 50 randomly selected subjects had their systolic blood pressure (SBP) recordedtwice—the first time at about 9:00 a.m. and the second time at about 2:00 p.m. If one were toexamine the relationship between the morning and afternoon readings, then one might expectthe correlation to be
2.If data set A of (x, y) data has correlationr= 0.65, and a second data set B has correlationr= –0.65, then
132The Practice of Statistics, 4/e- Chapter 3© 2011 BFW Publishers

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