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: [15.491, 60.283, 240.958, 155.995, 35.585, -55.875, 82.379, 142.503, 95.176, 85.281]
Example Output: 85.778

Example Input: [162.26, 79.268]
Example Output: 120.764

Example Input: [234.404, 162.933, 178.375, 10.683, 181.727, -50.587, 169.507, -72.896, 168.06, 238.363]
Example Output:
122.057