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: [-3.857, -93.605, 43.857, -73.731, 84.094, -24.492, -41.811, 115.552, 231.429, 130.678]
Example Output: 36.811

Example Input: [-2.772, 225.483, 211.749, 45.779, -82.623, 229.799, 107.783, 64.653]
Example Output: 99.981

Example Input: [-90.909, 245.831]
Example Output:
77.461