The accompanying graph shows the increasing number of motor vehicle registrations (cars and trucks) in the United States. Number of Motor Vehicle Registrations 300 250 200 150 100 50 1940 1950 1960 1970 1980 1990 2000 2010 Year Source: U.S. Federal Highway Administration, Highway Statistics, annual. Click here for the dataset associated with this question. Round your answers to one decimal place. a. Using 1945 as the base year, find a linear equation, using linear regression, that would be a reasonable model for the data. Let x = years since 1945 and y = registrations (in millions). The linear equation is y = b. Interpret the slope of your line in this context. On average, motor vehicle registrations have been v by million per year since 1945. c. What would your model predict for the number of motor vehicle registrations in 2007? How does this compare with the actual data value of 247.3 million? The equation predicts million motor vehicle registrations in 2007. This value is million v than the actual amount. d. Using your model, how many motor vehicles will be registered in the United States in 2010? The model predicts that million motor vehicles will be registered in the United States in 2010. Registrations (m ili