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: [14.587, 49.21, -21.274, -54.714, 243.935, 218.436]
Example Output: 75.03

Example Input: [135.962, 136.509, 77.88, 148.448]
Example Output: 124.7

Example Input: [-16.898, 37.874, -62.807, 233.541, 121.576, 65.272, -47.774, -69.595]
Example Output:
32.649