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: [-66.784, 220.149, -95.922, 246.835, 217.926, -13.146, 106.214, 91.375, 168.497, 173.521]

104.866