The table shows the retail market share of passenger cars from Ford Motor Company as a percent of the US market.

Year Market share

1980 17.2%
1885 18.8%
1990 20.0%
1995 20.7%
2000 20.2%
2005 17.4%

A mathmatical model for this data is given by
f(x) = -0.0206x^2 + 0.548x + 16.9
where x = 0 corresponds to 1980

1. Complete the following table:

x Market share f(x)
0 17.2
5 18.8
10 20.0
15 20.7
20 20.2
25 17.4

2. Sketch the graph of f and the market share data in the same coordinate system.

3. Use values of the modeling function f to estimate Ford's market share in 2010 and in 2015.

4. Write a brief verbal description of Ford's market share from 1980 to 2005.