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: [153.482, 150.917]
Example Output: 152.2

Example Input: [-95.352, -26.358, 34.234, 162.959, 239.101, 137.014]
Example Output: 75.266

Example Input: [155.346, -39.938, 179.964, -64.382, -97.582, -60.281, 12.876, 58.885, -13.011, 171.559]
Example Output:
30.344