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: [224.567, -42.213, 232.017]
Example Output: 138.124

Example Input: [229.461, -89.251, 170.954]
Example Output: 103.721

Example Input: [97.81, -33.944, 115.252, 79.101, 46.286, 182.807, 193.15, -9.527]
Example Output:
83.867