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: [203.231, 221.914, 29.718, 204.438, 105.014, -34.976, 5.602, 198.131, 243.99, 99.583]

127.664