Answer: the volume of the box is 31.25 cubic feet.
Step-by-step explanation: The volume of the box can be found by multiplying the area of the square base by its height:
Volume = Base Area x Height
Since the base of the box is a square with 2.5 feet wide on a side, its area can be calculated as:
Base Area = Side Length x Side Length = 2.5 ft x 2.5 ft = 6.25 sq. ft
And since the height of the box is 5 feet, the volume can be calculated as:
Volume = Base Area x Height = 6.25 sq. ft x 5 ft = 31.25 cubic feet
Therefore, the volume of the box is 31.25 cubic feet.