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: [15.293, 221.056, 241.387, 81.3, 102.644, 146.885, -33.65, -36.56, -69.176]
Example Output: 74.353

Example Input: [152.683, 147.968, 62.877, -44.254, 4.344]
Example Output: 64.724

Example Input: [4.435, 100.482, 125.267, -76.982, 9.994, 192.069, 54.099, -40.749]
Example Output:
46.077