Total personal income of the country (in billions of dollars) for selected years from 1957 to 2002 is given in the table. (a) These data can be modeled by an exponential function. Write the equation of this function, with x as the number of years after 1957. (b) If this model is accurate, what will be the country's total personal income in 2007? (c) In what year does the model predict the total personal income will reach $22 trillion? (a) The equation of an exponential function that models the data is y= (Use integers or decimals for any numbers in the expression. Round to three decimal places as needed.) Year Personal Income 1957 408.8 1967 830.9 1977 2310.3 1987 4876.7 1997 8421.6 2002 10,232.7