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: [-90.211, -60.08, 99.87, 18.704, 197.269, 173.722, 168.875]

72.593