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.
[-82.501, -99.665, 133.336, 126.104, -12.653, -23.215, 127.87, 23.473]