The number of revenue passengers enplaned in the United States over the 14-year period from 1994 to 2007 is shown in Table 1.7.(a) Graph a scatter plot of the data. Let x be the number of years since 1994. (b) From 1994 to 2000 the data seem to follow a linear model. Use the 1994 and 2000 points to find an equation of the line and superimpose the line on the scatter plot. (c) According to the linear model, in what year did the number of passengers seem destined to reach 900 million? (d) What happened to disrupt the linear model?