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: [-81.517, 126.001, 203.19, 236.819, 36.037, 152.691, -1.444, -37.296]
Example Output: 79.31

Example Input: [169.842, 149.921, 11.08]
Example Output:
110.281