As you might suspect since you're on the chapter on exponential functions, this situation can be modeled with an exponential equation (or a geometric sequence):
h(n) = a·bn
- h(n) = height on bounce n
- a = starting height = 512 ft
- b = common ratio = 1/2
- n = number of bounces = 8, where n is an integer
h(n) = 512·(1/2)n
h(8) = 512·(1/2)8
Plug in the numbers and compute the answer.