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: [207.449, 85.584, -55.048, -10.53, 30.755]
Example Output: 51.642

Example Input: [128.152, 95.16, 70.113, -16.853]
Example Output: 69.143

Example Input: [-76.794, -53.567, 105.147, 107.691, -72.23, 154.508, -2.909, 77.452]
Example Output:
29.912