Answer
The poverty threshold in 2005 was around $\color{blue}{\$9,992}$.
Work Step by Step
Since $x=0$ corresponds to 1999 and $x=1$ corresponds to 2000, then $x=6$ corresponds to 2005.
Substitute $6$ to $x$ to obtain:
$y=2.719(6^2)+196.1(6)+8718
\\y=2.719(36)+1176.6+8718
\\y=97.884 + 1176.6+8718
\\y=9992.484$
Thus, the poverty threshold in 2005 was around $\color{blue}{\$9,992}$
