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: [-79.597, 26.839, 178.556, -5.626, -37.294, 232.757, 136.684]
Example Output: 64.617

Example Input: [206.606, -76.103, -16.863, 44.126, 4.019, 15.088]
Example Output: 29.479

Example Input: [-98.048, 21.287]
Example Output:
-38.38