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: [-19.26, 130.53, 225.367, 179.475, -63.39]
Example Output: 90.544

Example Input: [120.236, 116.311, -13.268]
Example Output: 74.426

Example Input: [73.258, 119.058]
Example Output:
96.158