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: [184.51, 79.649, 31.606, -65.279, 1.231]
Example Output: 46.343

Example Input: [78.523, 239.098, 9.698, 69.94]
Example Output: 99.315

Example Input: [-23.758, -80.058, 138.371, 113.616, 208.431, -0.071]
Example Output:
59.422