Calculate Radius from Circumference: Finding r When C = 400

To solve the problem, we'll follow these steps:

• Step 1: Identify the given information.
• Step 2: Apply the circumference formula to find the radius.
• Step 3: Perform the necessary calculations to obtain the radius.

Now, let's work through each step:

Step 1: We know from the problem statement that the circumference of the circle is $C = 400$.

Step 2: We'll use the formula for the circumference of a circle: $C = 2\pi r$.

Step 3: Solving for $r$, we have: $r = \frac{C}{2\pi} = \frac{400}{2\pi}.$ Substituting $\pi \approx 3.14159$, $r = \frac{400}{2 \times 3.14159} = \frac{400}{6.28318} \approx 63.662.$

Therefore, the radius of the circle is approximately $\mathbf{63.662}$.