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.
[227.657, -51.382, 22.309, 130.1, 238.49, 74.387, -64.526, 207.509]