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: [-81.615, 70.057, -34.973, -14.992, 107.616, 211.919, 60.971, 223.577, 75.461]

68.669