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: [-84.771, 60.727, 165.566, 27.782, 159.929, 167.451, -64.15]
Example Output: 61.791

Example Input: [185.594, 89.215, 19.941, 23.299, 47.251]
Example Output: 73.06

Example Input: [202.511, 115.323, -27.64]
Example Output:
96.731