Answer
$\frac{1}{2}$ point per $\$1000$ increase in family income.
Work Step by Step
The graph contains the points $(50, 490)$ and $(90, 510)$.
To find the rate of change in the SAT critical reading scores with respect to family income, use the formula $\dfrac{\text{change in y}}{\text{change in x}}$.
rate of change = $\dfrac{510-490}{90-50}=\dfrac{20}{40}=\dfrac{1}{2}$
Thus, the rate of change in SAT critical reading scores with respect to family income is $\frac{1}{2}$ point per $\$1000$ increase in family income.
