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: [-2.425, -41.007, 142.975, 117.593, 142.875, -69.307, -38.932, 92.631, 158.921, 87.117]
Example Output: 59.044

Example Input: [185.594, 89.215, 19.941, 23.299, 47.251]
Example Output: 73.06

Example Input: [96.655, 210.608, 13.609]
Example Output:
106.957