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: [37.853, 78.283, 143.128, 82.561, 181.661, -89.154, 50.037]
Example Output: 69.196

Example Input: [-7.775, 55.997, 216.046]
Example Output: 88.089

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