Week 3 Homework - Chapters Seven, Eight, and Nine Capacity (Tb) Residual 1) (1 point each) To the right are the residuals for a regression of Price on 0.080 3.02 Capacity for selection of computer hard drives: 0.120 3.91 a) Which hard drive prediction was the least accurate? 0.250 5.35 0.320 18.075 1.000 -23.55 b) Two of the residuals are negative. What does that mean about those drives? Be specific and use the correct units (i.e. explain in context). 2.000 -21.475 4.000 14.666 2) (3 points) A survey was conducted in the United States and 10 countries of Western Europe to determine the percentage of teenagers who had used marijuana and other drugs. Below is the scatterplot. Summary statistics showed that the mean percent that had used marijuana was 23.9%, with a standard deviation of 15.6%. An average of 11.6% of teens had used other drugs, with a standard deviation of 10.2%. a) Do you think a linear model is appropriate? Explain. 30.0 + b) For this regression, R2 is 87.3%. Interpret this statistic in this context. 22.5 c) Write the equation you would use to estimate the percentage of teens Other Drugs (%) who use other drugs from the percentage who have used marijuana. 15.0 d) Explain in context what the slope of this line means. 7.5 e) Do these results confirm that marijuana is a "gateway drug," that is, marijuana use leads to the use of other drugs? Explain. 12.5 25.0 37.5 50.0 Marijuana (%)