Answer
$\$ 21142$
Work Step by Step
The poverty threshold $y$ in $2008$ can be estimated by the midpoint formula.
The $y$-coordinates for year $2003$ is $$y_1=\$18660y$$ and for year $2013$ is $$y_2=\$23624y$$
The midpoint of $y$-coordinate gives the poverty threshold estimate for the year $2008$.
$$\begin{align*}
y&=\frac{y_1+y_2}{2}\\
&=\frac{18660+23624}{2}\\
&= \dfrac{42284}{2}\\
&=21142
\end{align*}$$
We get $\$ 21142$ as the estimated value. The estimate is $\$21834-21142=\$692$ less than the reported value.
