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: [-25.972, -50.621, -29.364, 33.0, 174.639, 55.518, 2.267, 157.02, 178.689]

55.02