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: [175.015, 7.294, -30.146, 197.862, 76.557, 16.567, 176.301]
Example Output: 88.493

Example Input: [57.478, 212.225, -90.816, -10.092, 238.514, 60.36, 59.627]
Example Output: 75.328

Example Input: [186.218, 169.514, 33.47]
Example Output:
129.734