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: [185.805, 8.01, 151.056, 35.572, 51.884, 217.1, -0.547, 8.171]
Example Output: 82.131

Example Input: [82.992, 235.629, -36.094, -43.326, 27.531, -12.091, 212.495, 34.388]
Example Output: 62.69

Example Input: [26.857, -69.553, -37.942]
Example Output:
-26.879