Definition: 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.
Input: [-12.257, -2.874, 73.876, -68.286, 54.744, 123.908, 151.117, -62.612, -60.958, 91.189]

28.785