Definition: 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.
Input: [-27.297, -51.581, 46.026, -25.783, -26.542, 22.99, 228.991]

23.829