To find the area of a circle, you can use the formula:
\[ \text{Area} = \pi r^2 \]
where \( r \) is the radius of the circle.
Since the diameter is given as 21 miles, the radius \( r \) is half of the diameter:
\[ r = \frac{21}{2} = 10.5 \text{ miles} \]
Now, substitute \( r = 10.5 \) and \( \pi = 3.14 \) into the area formula:
\[ \text{Area} = 3.14 \times (10.5)^2 \]
Calculating \( (10.5)^2 \):
\[ (10.5)^2 = 110.25 \]
Now, calculate the area:
\[ \text{Area} = 3.14 \times 110.25 \]
\[ \text{Area} = 346.3875 \]
Rounding to the nearest hundredths place:
\[ \text{Area} \approx 346.39 \text{ mi}^2 \]
However, looking at your given options, the closest answer would be:
346.19 mi²
Thus, the correct response is:
346.19 mi squared.