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: [84.091, 17.564, 58.169, 6.482, 53.256, 216.444, 171.489]
Example Output: 86.785

Example Input: [228.031, -85.617, 36.164]
Example Output: 59.526

Example Input: [22.055, 33.53, 114.153, -38.531, -60.221, -34.133, -85.946, 171.323, 194.445]
Example Output:
35.186