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: [214.656, -82.183, 105.038, -34.9, -44.836, 143.236, 183.045, 160.483, 34.398]
Example Output: 75.437

Example Input: [185.617, -71.333, 131.491, 25.042]
Example Output:
67.704