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: [149.451, 230.29, 56.327, -72.328, -73.276, -90.669, 206.191, 87.481]
Example Output: 61.683

Example Input: [88.755, -64.951, 41.008]
Example Output: 21.604

Example Input: [-5.791, 37.676, 30.931, -19.175]
Example Output:
10.91