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: [208.757, -63.857, 124.458, 25.069, -39.093, -85.924, 112.747]
Example Output: 40.308

Example Input: [96.706, 239.918, 73.299, 68.184, 233.512, -76.407]
Example Output: 105.869

Example Input: [218.58, -87.215, 179.092, 180.514, -40.397]
Example Output:
90.115