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: [43.554, 122.733, 40.669, 163.641]
Example Output: 92.649

Example Input: [233.742, -71.075]
Example Output: 81.333

Example Input: [-9.243, 242.668, -26.051, 221.991, 140.845, 135.959, 21.123, 175.187]
Example Output:
112.81