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: [80.285, 75.631, 5.715, -68.695, 134.225, 22.744, 63.203, 136.862, 60.995]

56.774