C = 18 because find the radius by dividing by pi and square-rooting, then multiplying the radius by 2 to get the diameter. Then multiply by pi to get the circumference
To solve for the mean (average), you need to add together all the numbers then divide by how many numbers there are. In this case, there are 10 numbers.
because find the radius by dividing by pi and square-rooting, then multiplying the radius by 2 to get the diameter. Then multiply by pi to get the circumference