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: [121.069, 12.661, 159.825, -39.645, 6.609, 156.735, 110.054, 112.875]
Example Output: 80.023

Example Input: [-9.301, -10.629, 88.777, 68.965]
Example Output: 34.453

Example Input: [110.799, 16.436, -57.34, 139.423, 40.579, 66.312]
Example Output:
52.702