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: [-68.889, 87.274, 226.539, -68.827, 28.425, 213.866, -79.699, 147.004, -69.122]

46.286