The number of TV channels is increasing. The bar graph shows the total channels available...

The number of TV channels is increasing. The bar graph shows the total channels available in the average U.S. household from 2000 through 2006.

Number of TV Channels in the Average United States Household

Source: Nielsen Media Research

Here are two mathematical models for the data shown by the graph. In each formula, N represents the number of TV channels in the average U.S. household x years after 2000.

a. Which model best describes the data for 2000?

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b. Does the polynomial model of degree 2 underestimate or overestimate the number of channels for 2006? By how many channels?

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c. According to the polynomial model of degree 1, how many channels will the average household have in 2010?