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: [-48.174, -65.43, -35.345, -39.192, -88.741, 81.764, 113.912, 85.061, 139.932]

15.976