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: [14.991, -71.897, 59.429, -23.24, 231.819, -61.55, -34.507, -47.27, 95.473]

18.139