Definition: In this task you will be given a list of numbers and you need to find the mean (average) of that list. The mean of a list can be found by summing every number in the list then dividing the result by the size of that list. The output should be rounded to 3 decimal places.
Input: [204.455, 97.369, 66.08, -33.331, 234.506, 237.162, 132.311, 226.079, -12.993]

127.96