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: [150.437, -3.837, 129.078, -54.453, -99.098, 200.922, 5.328, 29.431, 145.114]

55.88