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: [15.799, 6.545, 101.018, -76.074, 51.291, -58.732, 131.857, -36.93, 131.423]

29.577