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: [103.885, 191.867, 82.228, 177.708, 136.093, -17.022]
Example Output: 112.46

Example Input: [-77.226, 44.49]
Example Output: -16.368

Example Input: [134.223, -5.071, 199.451, 83.215, 227.848, 225.195, 247.03]
Example Output:
158.842