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: [4.808, 205.011, 171.006, -83.794, 174.586, 239.34, -47.787, 15.572, 66.299]

82.782