To calculate the circumference \( C \) of a circle using the formula \( C = \pi d \), where \( d \) is the diameter, we can substitute the values given:
- The diameter \( d = 7 \) ft.
- We use \( \pi \approx 3.14 \).
Now plug in the values:
\[ C = \pi d = 3.14 \times 7 \]
Calculating that:
\[ C = 3.14 \times 7 = 21.98 \text{ ft} \]
Thus, the circumference of the circle is approximately:
\[ C \approx 21.98 \text{ ft} \]