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: [-13.364, -79.694, -23.447, -46.589, 144.97, -28.554, 212.875, 208.512, 171.399]

60.679