From 1990 through 1996, average monthly cable TV bills were as shown below.

Year                           Average Bill

1990…………………….……….. $17.60

1991…………………….………..  19.20

1992…………………….………..  20.62

1993…………………….………..  22.49

1994…………………….………..  21.60

1995…………………….………..  23.07

1996…………………….………..  25.50

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?