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: [-51.603, 117.351, -67.451, 218.664, 68.981, 167.005, -53.851, 104.996]
Example Output: 63.012

Example Input: [-19.13, 98.86, 158.686, 230.23]
Example Output: 117.161

Example Input: [-56.947, -16.775, 192.173, 78.808, 194.151]
Example Output:
78.282