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: [207.476, -80.931, -15.605, -15.357, 173.462, -61.739, 249.542, -96.57, -46.58]

34.855