#### Answer

The model overestimated the percentage shown for 2009 by $\:0.4\%$.

#### Work Step by Step

Since the model represents the percentage of U.S. adults who got a flu
shot $x$ years after $2005$, the value of $x$ would then be:
$$x = 2009-2005$$$$x=4$$
Substituting this to the given model:
$$F = 28 + 6x - 0.6x^{2}$$ $$28 + 6(4) – 9.6 = \:42.4\%$$
Since the value reflected on the graph is only $\:42\%$. Therefore, the model overestimated the percentage shown for 2009 by $\:0.4\%$.