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: [-16.897, 83.566, 220.893, 234.562, 79.99, 152.134, 210.173, -88.351, 13.81]

98.876