Answer: 5 feet.
Step-by-step explanation:
Remember that the lenghts of the sides of a regular octagon are equal.
You can observe in the figure that the lenght of a side of the regular octagon is 1.25 inches.
Let be "s" the actual length of a side of the regular octagon.
Knowing that the scale drawing has a scale of 1 inch 4 feet, you can find the actual lenght of a side of this regular octagon with:
Therefore, the actual length of a side of the octagon is 5 feet.