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: [-38.715, 205.647, 66.034, 49.8, -92.051, 111.017, 149.689]
Example Output: 64.489

Example Input: [159.965, 172.082]
Example Output: 166.024

Example Input: [232.016, -96.162, 139.488, 225.387, 240.259, 135.51, 203.119]
Example Output:
154.231