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: [-50.144, 0.802]
Example Output: -24.671

Example Input: [99.278, 72.353, -21.292]
Example Output: 50.113

Example Input: [5.519, 194.532, -80.402, -36.566, 4.818]
Example Output:
17.58

