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: [-79.521, 169.962, 120.036, -71.612, -53.261, -90.734, -35.559, 140.419, 25.016]
Example Output: 13.861

Example Input: [208.678, 219.921, 113.318, 23.83, -42.88, -32.702, -36.191, 117.84, 91.988]
Example Output: 73.756

Example Input: [16.957, 247.704, 88.678, -40.547, -16.984]
Example Output:
59.162