It would be taking the median, since the data distribution is skewed to the right.
The reason for this is that half of the numbers occupy a small space of between 7 and 8. Therefore, the extreme values on the right can give you a misrepresentation of the data if you use the mean, which is why is would be more accurate to use the median instead of the mean.
The answer would be 250000
Since you already know the radius multiply it by itself(20*20=400)then multiply that amount by 3.14.(formula: 3.14*(radius*radius)
X =3 hope it helps..................................