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: [-45.826, -27.376, 126.782, -28.164, 213.819, 186.676]
Example Output: 70.985

Example Input: [229.28, 202.632, 129.717, 211.459, 203.204]
Example Output: 195.258

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