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: [-88.637, 110.942, 169.271, 131.162, 132.478, 72.08, 241.487, 169.896, 216.266]

128.327