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: [84.444, 53.979, -73.239, 22.678, 152.957, -19.951, 24.166, 168.351, -53.939]

39.938