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: [-90.211, -60.08, 99.87, 18.704, 197.269, 173.722, 168.875]
Example Output: 72.593

Example Input: [47.595, -7.171, 4.333, 160.025, 152.275, 90.23, 128.643, 145.181]
Example Output: 90.139

Example Input: [29.833, 170.246, 222.43, -87.927, -70.09, 8.335, 90.479, -22.306]
Example Output:
42.625