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: [245.271, 40.965, 133.913, 212.104]
Example Output: 158.063

Example Input: [-31.241, 73.981, 127.71, 166.275, 35.028, -10.432]
Example Output: 60.22

Example Input: [46.136, 37.75, 217.657, -57.671, 202.793, 124.039]
Example Output:
95.117