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: [24.119, 239.006, 239.873, 236.27, 134.34]
Example Output: 174.722

Example Input: [-21.617, 220.257, 168.97, -35.044, 108.975]
Example Output:
88.308