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: [66.666, -70.196, -39.152]
Example Output: -14.227

Example Input: [223.847, 115.483, 148.407, -44.824, 99.251, 36.833, -45.949]
Example Output: 76.15

Example Input: [124.963, -89.484, 8.032, 146.975, -10.09, 82.917, 182.295]
Example Output:
63.658