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: [173.421, -39.421, 120.886, -35.706, -64.922, 108.501, 132.542, 50.402]

55.713