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: [208.757, -63.857, 124.458, 25.069, -39.093, -85.924, 112.747]
Example Output: 40.308

Example Input: [-78.906, 119.863, 44.561, 1.523]
Example Output: 21.76

Example Input: [160.567, 148.731]
Example Output:
154.649