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: [161.683, 162.041, 187.429, -79.681, 60.809, 225.806]
Example Output: 119.681

Example Input: [79.132, 226.507, 40.498, 100.658, 75.361]
Example Output: 104.431

Example Input: [-6.462, -14.924, 172.464, 225.877, 55.181]
Example Output:
86.427