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: [192.529, -67.249, 123.707, 41.987, 11.587, 202.189, 12.989]
Example Output: 73.963

Example Input: [82.748, 43.804, -13.469, 226.705, -7.478]
Example Output: 66.462

Example Input: [211.052, 6.088, 216.055]
Example Output:
144.398