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: [207.041, -65.569, 55.112, 47.798, 25.728, 60.579, 12.774, -88.361, 103.728]

39.87