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: [65.486, -51.995, 170.628, -23.998, 83.128, -57.38, 130.737, 214.738]
Example Output: 66.418

Example Input: [188.006, 117.583, 51.262]
Example Output: 118.95

Example Input: [110.612, 97.116, 204.936, -46.173, 74.248, -69.562]
Example Output:
61.863