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: [127.796, -50.299, -71.687, 177.299, 38.169, 148.763, 154.663, -56.403, -15.171]

50.348