Final answer:
The actual length of the box is 12 feet.
Step-by-step explanation:
To find the actual length of the box, we need to use the scale conversion. The scale is 1 inch to 3 feet. So, for every 1 inch on the drawing, the actual length is 3 feet. In this case, the length of the box in the drawing is 4 inches, so we can multiply it by the scale factor of 3 feet per inch. 4 inches * 3 feet/inch = 12 feet. Therefore, the actual length of the box is 12 feet.