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: [185.594, 89.215, 19.941, 23.299, 47.251]
Example Output: 73.06

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

Example Input: [-90.937, -71.354, 23.105, 52.417, 122.361, 140.597]
Example Output:
29.365