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: [73.603, -84.154, 222.739, 205.594, 215.842]
Example Output: 126.725

Example Input: [121.069, 12.661, 159.825, -39.645, 6.609, 156.735, 110.054, 112.875]
Example Output: 80.023

Example Input: [90.21, 237.481, 235.732, 192.699]
Example Output:
189.031