The formula for the average value is
(1/b-a)http://upload.wikimedia.org/math/4/0/c/40c4f3fd4e90d666f43f275de6264a1e.png
and the midpoint rule is the same as the midpoint sum except that dt is factored out of the equation.
dt = (b-a/n)
midpont sum = f(t0)dt +...f(tn)dt and with the
average...