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: [245.2, 202.565]
Example Output: 223.882

Example Input: [-94.649, -47.045, 244.483, 5.338, 243.43, -3.442, 16.366]
Example Output: 52.069

Example Input: [183.968, 72.9, -62.314, 191.214, 78.442, 29.207]
Example Output:
82.236