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: [128.795, 160.268, 205.1, -28.21, -13.043, 69.155, 104.411, -81.247, -32.44]

56.977