The words "around the outside" make me stupid, because it is not a math term. I would understand "around the perimeter" . . . In my view, it is much better description. If you accept this conception, then calculate the perimeter P = 4*6 = 24 feet, convert it to inches P = 24*12 inches, divide by 6 to get N == 24*2 = 48 intervals between the plants. Thus your answer is 48 plants, same as the number of intervals. Answer. 48 plants.