4. James Andino, an economist working for the government, is trying to determine the demand function for passenger car fuel in the United States. James developed a model that used the ac tual price of a gallon of regular gasoline to predict motor fuel consumed per year. He was able to explain 83.5% of the variation in fuel consumption with his model. James has decided to add a variable representing the population of the United States to the model. Determine whether serial correlation is a problem. The data are shown in Figure 7.14. Figure 7.14 Gasoline Price and Consumption Gallons Price Population 78.8 0.39 211.9 85.1 0.53 213.9 76.4 0.57 216 79.7 0.59 218 80,4 0.62 220.2 81.7 0.63 222.6 77.1 0.85 225.1 71.9 1.19 227.7 71 1.33 230.1 70.1 1.26 232.5 69.9 1.22 234.8 68.7 1.21 236,3 69.3 1.16 238.5 71.4 0.92 240.7 70.6 0.95 242.8 71.7 0.95 245.1