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: [-53.097, 130.791, 218.881, 162.561, -20.497, 82.655, -64.567, 131.705, 79.607]

74.227