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.
[-16.12, 27.442, -69.009, 28.682, 110.187, 230.261, -76.728, 136.926]