Answer
$MAD=544.25~dollars$
The sample standard deviation ($712$ dollars) is substantially greater then the mean absolute deviation. Maybe this difference is due to $n-1$ in the denominator of the sample standard deviation. If you change the $n-1$ by $n$ you will find $s=616.65~dollars$. It should be a good execise to compare the sample standard deviation and the mean absolute deviation for large values of $n$.
Work Step by Step
$x̅=2025.25$ (see problem 11)
$MAD=\frac{Σ|x_i-x̅|}{n}=\frac{|2529-2025.25|+|1889-2025.25|+|2610-2025.25|+|1073-2025.25|}{4}=544.25$
