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: [-4.749, 102.787, -45.229, 184.111, 221.888, 22.727, 20.887, 34.094]
Example Output: 67.065

Example Input: [162.26, 79.268]
Example Output: 120.764

Example Input: [-91.439, 241.636, 17.219, 126.501, 234.462, 184.828, -34.478]
Example Output:
96.961