To find the circumference of a circular walkway, you can use the formula:
\[ C = \pi d \]
where \( C \) is the circumference and \( d \) is the diameter.
Given that the diameter of the walkway is 12 ft, we can substitute this value into the formula:
\[ C = \pi \times 12 \]
Now, using the approximate value of \( \pi \) as 3.14:
\[ C \approx 3.14 \times 12 \approx 37.68 \]
Rounding to the nearest tenth of a foot, the circumference is:
\[ C \approx 37.7 \text{ ft} \]
Thus, the circumference of the outside edge of the concrete walkway is approximately 37.7 ft.