To determine the length of the third side of the triangle, we can use the triangle inequality theorem, which states that the sum of the lengths of any two sides of a triangle must be greater than the length of the third side.
In this case, we have two sides of lengths 24 ft and 15 ft. Let x be the length of the third side. Then, according to the triangle inequality theorem, we have:
24 + 15 > x
39 > x
and
15 + x > 24
x > 9
Combining these inequalities, we have:
9 < x < 39
Therefore, the length of the third side of the fence could be any value between 9 ft and 39 ft, but it cannot be exactly 7 ft, 8 ft, or 10 ft. Out of the given options, the closest value to the range is 9 ft.