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: [113.238, 247.072, -31.448, -33.563, 74.519, 67.841]
Example Output: 72.943

Example Input: [-44.471, 208.445, 208.318, -34.134]
Example Output: 84.54

Example Input: [-67.466, 148.217, 90.861, 65.54, -82.837, 38.928, -22.938, 135.484]
Example Output:
38.224