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: [-44.471, 208.445, 208.318, -34.134]
Example Output: 84.54

Example Input: [127.522, 232.86, 46.593]
Example Output: 135.658

Example Input: [187.908, -10.534, -70.911, -26.095, 56.286, 93.628, -99.012, 157.864]
Example Output:
36.142