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: [-91.531, 115.044, -34.155, 178.455, 0.682, 90.689, -60.965, 15.051, 224.379]

48.628