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.
[-33.269, 67.423, 66.702, 77.302, -35.234, 92.894, 123.068, -78.573, 123.346, 122.928]