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: [-51.496, 56.177, 55.554, -17.425, -6.185, 3.721]
Example Output: 6.724

Example Input: [166.967, 154.381, -19.741, 157.124]
Example Output: 114.683

Example Input: [51.355, 33.6, 155.027]
Example Output:
79.994