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: [194.026, 179.483, 77.885, 111.339, 234.419, 138.685]
Example Output: 155.973

Example Input: [70.568, -80.778]
Example Output: -5.105

Example Input: [-82.655, 69.809, 141.521, 57.91, 8.583]
Example Output:
39.034