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: [212.456, 6.972, -59.399, -83.342, 215.038, -97.851]
Example Output: 32.312

Example Input: [210.345, 91.115]
Example Output: 150.73

Example Input: [-51.128, 79.354, 150.078, 125.395]
Example Output:
75.925