A cross-section of an airplane wing is shown. Measurements of the thickness of the wing, in centimeters, at 19-centimeter intervals are 5.7, 20.5, 27.2, 29.0, 27.3, 26.9, 23.7, 20.4, 16.3, 8.2, and 2.3. Use the Midpoint Rule with $n = 5$ to estimate the area of the wing's cross-section if $a = 190$. (Assume the thickness of the edges is nonzero.) cm$^2$ a cm