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: [183.332, -51.581, -15.684, 140.965, 37.376, 37.734, 71.356]
Example Output: 57.643

Example Input: [118.319, 70.462]
Example Output: 94.39

Example Input: [38.418, 160.909, -2.36, 88.783, 234.261, -12.12]
Example Output:
84.648