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: [155.346, -39.938, 179.964, -64.382, -97.582, -60.281, 12.876, 58.885, -13.011, 171.559]

30.344