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: [85.354, -22.629, 51.171, 238.376, 177.126, -90.135, -84.086, 175.426, -80.74]
Example Output: 49.985

Example Input: [-19.26, 130.53, 225.367, 179.475, -63.39]
Example Output: 90.544

Example Input: [157.14, 120.799, -55.651, -50.479, 89.067, 192.279, 57.227, 137.972]
Example Output:
81.044