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: [166.42, 11.757, 105.453, 25.541, 129.104, 218.808, -97.374]

79.958