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: [-6.485, 220.59, 172.044, -34.995, 247.407, 116.292, -39.344]

96.501