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: [146.748, -23.736, 49.614]
Example Output: 57.542

Example Input: [34.718, 46.286, 107.22, 181.771, -27.702, -66.747]
Example Output: 45.924

Example Input: [-82.879, -82.239, 22.652, 207.818, 148.773, 233.502]
Example Output:
74.604