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: [29.292, 193.26, -48.646]
Example Output: 57.969

Example Input: [192.335, 189.22, 235.216, 130.727, 222.285]
Example Output: 193.957

Example Input: [37.372, 52.175, 140.442]
Example Output:
76.663