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: [-66.461, -23.723, -86.436, -25.52, 17.227, -16.517, 120.023, 197.06, 111.925]

25.286