Answer: -64
Step-by-step explanation:
h(t) = -16t² + 128t
dh/dt = -32t + 128
At t = 4,
dh/dt= -16(4)² + 128 = 0
At t = 4, dh/dt = 0
At t = 8,
dh/dt = -16(8)² + 128 = -128
At t = 8, dh/dt = -128
The rate of change of h is constant, the average rate change is
(0 - 128) / 2 = -64