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: [220.502, 120.286, 84.602, 152.56, 67.934, -15.515, 75.274, 165.703, 61.737]

103.676