To find the diameter \( d \) of a circle using the circumference \( C \), you can use the formula:
\[ d = \frac{C}{\pi} \]
Given that the circumference \( C = 21.98 \) feet and using \( \pi \approx 3.14 \), the calculation for the diameter \( d \) is as follows:
\[ d = \frac{21.98}{3.14} \]
Now, performing the division:
\[ d \approx 7.0064 \text{ ft} \]
Rounding to two decimal places, the diameter \( d \) is approximately:
\[ d \approx 7.01 \text{ ft} \]