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: [56.855, -15.42, 166.529, 79.81, 18.164, 127.812, 129.26, 60.611, 87.934]

79.062