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: [-98.69, -9.429, 137.637, 11.095, 31.581, -54.876, -62.991, 132.5, 140.025]

25.206