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: [-79.521, 169.962, 120.036, -71.612, -53.261, -90.734, -35.559, 140.419, 25.016]

13.861