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: [-77.705, 141.542, 119.674, -41.002, -51.183, -73.05, -46.322, 79.157, -19.117]

3.555