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: [-61.513, 183.183, 185.709, 179.801, 194.827, 91.62, 229.939, -7.981, 123.813, -77.981]
Example Output: 104.142

Example Input: [-33.534, 58.157, 70.753, 71.611, 109.161, 24.123, 52.98, -81.441]
Example Output:
33.976