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: [218.807, 72.849, 7.838, 124.81, 45.929, 239.888]
Example Output: 118.354

Example Input: [1.435, 246.462, 5.433, -3.093, 31.948, 113.344, 41.816, 43.437, -93.129, 116.292]
Example Output: 50.395

Example Input: [-3.267, 58.572, -51.668, -39.46, 71.943, 16.452, -81.657]
Example Output:
-4.155