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: [64.523, 131.207, -30.223, -95.659]
Example Output: 17.462

Example Input: [-32.499, 21.999, 235.435, 58.638, -57.806, 224.947, 74.782]
Example Output: 75.071

Example Input: [90.167, 145.229, -7.463, -49.818, 212.851, 220.193, 36.707, 68.67, -82.583, -84.099]
Example Output:
54.985