The National Association of Railroad Passengers has reported the following data describing U.S. commuter train ridership.

                                                                    Year
                            1995         1996         1997         1998         1999         2000
            Riders     42.2         45.9             48.5         54.0         58.3           61.6 million

For the ridership data shown above:
a. Fit a linear trend equation to the time series. Using this equation, determine the trend estimate for 2010.
b. Fit a quadratic equation to the time series, then use the equation to determine the trend estimate for 2010.
c. Which of the preceding equations is the better fit to the time series if the MAD criterion is used? If the MSE criterion is used?