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: [79.016, 157.142, -57.985, 210.295, 133.323, 100.855, -40.084]

83.223