The area of a circle is pi times radius^2
So if you use 3.14 x 16, it gives you approximately 50.264
18,38,38,40,44,44,44,46,48....
the mean with the outlier (18) included is : 360/9 = 40
38,38,40,44,44,44,46,48
the mean with the outlier (18) excluded is : (360 - 18) / 9 = 342/9 = 38
so when the outlier is removed, the mean is 2 points less
I would say between 1m and 6m
In case you don't know your times-3 numbers well enough to recognize the answer right away, you can check the second data point.
.. a. 2^3 = 8 ≠ 6
.. b. 3^2 = 9 ≠ 6
.. c. 3*2 = 6
.. d. 2 +3 = 5 ≠ 6
Only selection C makes sense.