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: [-16.768, 0.229, 14.955, -32.161, -40.159, -81.113, 34.071]

-17.278