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: [-38.715, 205.647, 66.034, 49.8, -92.051, 111.017, 149.689]
Example Output: 64.489

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

Example Input: [-74.074, -34.113]
Example Output:
-54.094