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: [7.177, 87.281, 34.876, -11.309, 171.893, -11.798, 15.157]

41.897