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: [170.667, 186.784, -36.763, 51.763, 107.885, -23.866, 29.933, 129.331, -95.257, 121.173]

64.165