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: [-3.281, 84.204, -74.415, 151.616, 14.048, -98.313, 95.625, -79.981]
Example Output: 11.188

Example Input: [30.7, 241.916, 245.677, -26.708, 212.446, 81.786, 208.412, 237.096, 155.359]
Example Output: 154.076

Example Input: [163.378, 63.843, 54.946, -61.486, 218.634, 129.505, 16.536]
Example Output:
83.622