Final answer:
The minimum thickness of the metal is determined by calculating the volume of the box.
Step-by-step explanation:
The minimum thickness of the metal for a 6x4x3 1/4 sheet steel box can be determined by calculating the volume of the box.
To find the volume, we multiply the length, width, and height of the box: 6 in. x 4 in. x 3.25 in. = 78 in³.
Therefore, the minimum thickness of the metal should be at least 78 cubic inches to accommodate the volume of the box.