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: [209.391, -20.297, -96.97, 245.149, 236.303, 36.406, -16.209, 93.283, -80.945, 75.328]

68.144