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: [126.548, 141.963, -79.366, -40.283, 30.655, -66.024, 182.809, 40.87, 152.327]

54.389