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: [-13.739, 48.4, -25.661, 184.205, -59.52, 105.713, 120.169, 154.053, 30.726]

60.483