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: [-58.447, 213.433, 187.859, 103.704]
Example Output: 111.637

Example Input: [15.748, -13.369, -79.943, -2.78, 169.174, 101.44, -84.923, 189.589, 83.541, -37.629]
Example Output: 34.085

Example Input: [-23.938, 180.002, 99.059, 120.407, 49.388, -89.173, 13.758, 167.814, 80.522]
Example Output:
66.427