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: [79.04, 110.342, 208.846, 132.702, 48.832, -81.929]
Example Output: 82.972

Example Input: [100.422, 199.731, 138.971, 95.515, 9.517]
Example Output: 108.831

Example Input: [37.118, 57.376, -12.165, -44.805, -81.242]
Example Output:
-8.744

