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: [-24.069, 49.942, -56.199, 147.337, 81.429, 198.62, -91.886, 33.842, -16.712, -51.661]
Example Output: 27.064

Example Input: [222.94, 54.014, 232.208, -16.089, 214.915, 2.232]
Example Output: 118.37

Example Input: [-29.607, 44.351, 192.283, 206.633]
Example Output:
103.415