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: [-81.432, -63.059, 150.144, 55.203, 215.405, -89.797, 72.946]
Example Output: 37.059

Example Input: [26.857, -69.553, -37.942]
Example Output: -26.879

Example Input: [-52.125, -29.243]
Example Output:
-40.684