Check Your Understanding: Fueleconomy.gov gives the city and highway fuel economy for all makes and models of vehicles back to 1984. The table gives the city and highway fuel economy (mpg) for a random sample of ten 2021 vehicles. City fuel economy 14.4 24.3 27.2 29.9 20.4 28.8 20.9 23.2 28.6 25.4 (mpg Highway fuel 25.5 37.4 36.5 45.5 28.7 46.1 33.6 38.3 41.3 35.3 economy (mpg) a. Calculate the equation of the least-squares regression line. b. Make a residual plot for the linear model in Question 1. c. What does the residual plot indicate about the appropriateness of the linear model? Explain your answer. STATS MEDICName: Hour: Date: How many iphones will be sold? Here is the data of all iPhone sales during their opening weekends: iPhone Year Units Sold (millions) Original 2007 0.5 3G 2008 3Gs 2009 1 4 2010 1.7 4S 2011 4 5 2012 5 5C, 5S 2013 9 6, 6 Plus 2014 10 6S, 6S Plus 2015 13 1. Use stapplet.com to create a scatterplot of the data with year as the explanatory variable and units sold as the response. Sketch the scatterplot in the space above. 2. Describe the form of the distribution. 3. Use the applet to find the least squares regression line. Write the equation below and graph it on your scatterplot above. 4. Use the least squares regression line to calculate the residual for 2007. Interpret the residual. 5. Complete the table below. 6. Graph the residuals on the axes Year Actual Predicted Residual Delow. This is called a residual plot. Units Sold Units Sold 2 (millions (millions 2007 0.5 2008 2009 2010 1.7 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2011 4 -1 2012 5 2013 9 -2 2014 10 2015 13 7. For which points was the actual greater than the predicted? Which were less than predicted? Identify these on the graph. 8. Do you think the regression line is a good fit for the data? Why or why not? Explain using the residual plot. STATS MEDIC