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: [126.177, 120.225, 231.498, 170.694, 34.361, 101.823, -21.468, 234.339]
Example Output: 124.706

Example Input: [231.159, 217.795, 230.676, -11.951, -82.697, 31.413]
Example Output: 102.732

Example Input: [-45.613, -3.911, 216.85, -40.965, 54.086, -17.634, 199.144, 79.58]
Example Output:
55.192