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.

Example Input: [225.697, 75.029]
Example Output: 150.363

Example Input: [103.885, 191.867, 82.228, 177.708, 136.093, -17.022]
Example Output: 112.46

Example Input: [81.09, 67.064, 134.568, 153.026, 93.382, -28.117, 27.819, -24.987]
Example Output:
62.981

