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: [49.035, -81.115, 27.419]
Example Output: -1.554

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

Example Input: [206.429, -12.258, -80.864, 165.434, 37.409, -39.683]
Example Output:
46.078