Answer:
3 ft
Explanation:
The volume of the box is given by the formula ...
V = Bh
where B is the base area and h is the height. Solving for h, we get ...
h = V/B
Filling in the numbers gives us the height:
h = (20 1/4 ft^3)/(6 3/4 ft^2) = (81/4)ยท(4/27) ft = 3 ft
The height of the box is 3 feet.