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: [227.404, 94.456, 233.241, 147.762, -31.667, -62.22, -93.912]
Example Output: 73.581

Example Input: [193.91, 159.502, 226.363, 152.723, 47.512, 74.563, 40.762, -60.456, 87.324, 80.779]
Example Output: 100.298

Example Input: [146.748, -23.736, 49.614]
Example Output:
57.542