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.
[189.041, -64.259, 101.875, 135.905, 101.085, 137.593, -5.653, 223.83]