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: [-40.016, 117.495]
Example Output: 38.74

Example Input: [70.553, 193.054, 166.173, 115.812]
Example Output: 136.398

Example Input: [72.066, 224.552, 85.005, 249.093, 20.946, 76.286, 56.95, 193.66, -27.553]
Example Output:
105.667