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: [-40.509, 201.39]
Example Output: 80.44

Example Input: [-38.715, 205.647, 66.034, 49.8, -92.051, 111.017, 149.689]
Example Output: 64.489

Example Input: [161.691, 192.391, 194.275, 142.11, -44.836, -6.556]
Example Output:
106.512