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: [139.608, 17.516, 100.5, -51.362, 57.462, -77.569, -95.41, -24.339, -96.579]
Example Output: -3.353

Example Input: [-50.144, 0.802]
Example Output: -24.671

Example Input: [56.33, -49.847, 176.505, -72.615, 133.421, 231.206, 29.368, 181.205]
Example Output:
85.697