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: [-35.762, 139.096, -42.495, 212.873, 171.092, 51.289, -17.019]

68.439