Federal debt the federal debts d (in billions of dollars) of the united states at the end of each year from 2000 through 2009 are shown in the table.
year 2000 2001 2002 2003 2004
debt 5629 5770 6198 6760 7355

year 2005 2006 2007 2008 2009
debt 7905 8451 8951 9986 11,876

a model for these data is given by y = 5364.1e0.0796t, where t represents the year, with t = 0 corresponding to 2000.
(a) how well does the model fit the data?
(b) find the linear model for the data. how well does the linear model fit the data? which model, exponential or linear, is a better fit?
(c) use both models to predict the year in which the federal debt will exceed 18,000 billion dollars.