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: [30.7, 241.916, 245.677, -26.708, 212.446, 81.786, 208.412, 237.096, 155.359]
Example Output: 154.076

Example Input: [89.776, -37.895, -45.315, 75.805, 144.052, 150.156]
Example Output: 62.763

Example Input: [58.969, -18.162, 244.152, -7.49, -94.239, 70.388, 168.163, 37.53]
Example Output:
57.414