A cube has equal sides so the volume is calculated as
V= a x a x a verses the Volume of a box which equals
lenght x height x width
Now we take the 3rd root of 68.921 by 3✔ ️because all sides are equal on a cube. We have 4.10 ft.
Check:
4.10 ft x 4.10 ft =
16.81 ft^2
16.81 ft^2 x 4.10 ft = 68.921 ft^3