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: [91.408, 178.508, 77.081, 13.419, 185.372, 158.828]
Example Output: 117.436

Example Input: [79.978, -44.051, 200.217, 142.486, -89.194, 55.999, 165.078, -3.615, 0.12, -44.323]
Example Output: 46.27

Example Input: [198.943, 16.473, -44.865, 243.93, 111.699, 60.814, -89.371]
Example Output:
71.089