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: [-19.769, 147.929, -36.133, 201.287, 28.528, -6.089, 122.533, 127.892, -36.662]
Example Output: 58.835

Example Input: [20.796, 39.383, -26.46, -27.224, 89.591, 87.502, 211.781, 127.87, 223.38]
Example Output: 82.958

Example Input: [185.774, 65.296, 178.62, -19.559, 162.832]
Example Output:
114.593