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.
[104.363, 54.247, 68.896, 103.333, 202.871, 187.953, 210.963, -54.023]