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: [210.345, 91.115]
Example Output: 150.73

Example Input: [126.453, 169.516, 109.837, 208.695, 113.906, 56.894, 171.345, 126.81]
Example Output: 135.432

Example Input: [10.724, -65.993, 107.56, 154.38, 117.135, 114.495, 11.544]
Example Output:
64.264