The volume of a rectilinear shape is the product of length, width, and height. This formula can be solved to find the height from the other given values.
.. V = lwh
.. h = V/(lw)
For this problem, we want the value of 8h, so we have
.. 8h = 8V/(lw)
.. = 8(10 2/3 ft^3)/((4 ft)(1 1/3 ft))
.. = (256/3 ft^3)/(16/3 ft^2)
.. = 16 ft
The height of the stack of bales is 16 feet.