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: [-40.016, 117.495]
Example Output: 38.74

Example Input: [169.737, 56.872, 102.557, -9.77]
Example Output: 79.849

Example Input: [207.165, 246.399, 44.821, -21.671]
Example Output:
119.178