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: [199.728, -96.25, -77.714]
Example Output: 8.588

Example Input: [1.435, 246.462, 5.433, -3.093, 31.948, 113.344, 41.816, 43.437, -93.129, 116.292]
Example Output: 50.395

Example Input: [96.309, 244.35, 155.842, 66.28, -81.853, 75.484]
Example Output:
92.735