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: [116.268, 173.27, 228.827, 52.695, 66.445, -34.051, 152.137]
Example Output: 107.942

Example Input: [-30.66, 134.777, 39.637, -41.053, 60.502, -99.875, -32.055, 51.52, 216.645, 11.994]
Example Output: 31.143

Example Input: [-66.288, 234.53, 204.285, 136.439]
Example Output:
127.242