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 $21
trillion?