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: [123.511, 37.811, 249.595, -25.324]
Example Output: 96.398

Example Input: [117.913, 21.456, 98.401, -32.801, -20.798, 182.745, 201.277]
Example Output: 81.17

Example Input: [204.239, 162.75, -27.965, 90.425, 147.912, 25.99, -22.763, 109.311]
Example Output:
86.237