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: [-4.969, 232.548, 81.586, 13.448, -85.528, -1.661, -76.971]
Example Output: 22.636

Example Input: [72.755, 233.932, 245.785, 92.401]
Example Output: 161.218

Example Input: [149.961, 203.86]
Example Output:
176.91