The average rate of change of h(t) = -16t ² + 40t + 4 between t = 0 and t = 2 is
(h (2) - h (0)) / (2 - 0) = ((-16×2² + 40×2 + 4) - (-16×0² + 40×0 + 4)) / 2
… = ((-64 + 80 + 4) - 4) / 2
… = 16 / 2
… = 8
h(t) is measured in feet, so the average rate of change is measured in feet per second, so it's 8 feet per second.
