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: [28.128, 24.252, 22.054, -87.294, 49.547, -7.212, 222.62, 168.289, -75.692]

38.299