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: [-19.13, 98.86, 158.686, 230.23]
Example Output: 117.161

Example Input: [202.411, 127.775, 165.721, -41.545, 113.127, 229.974, 111.13, 208.686, 92.744, 36.522]
Example Output: 124.654

Example Input: [-48.917, 240.011, 168.755]
Example Output:
119.95