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

Example Input: [25.58, 99.319, 165.429]
Example Output: 96.776

Example Input: [-51.804, -28.782, 31.225, 196.925, 227.008, 189.143]
Example Output:
93.952