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: [91.118, 17.484, 235.926, 125.736, 18.112, 221.52, 55.133, 234.247, 50.777, -4.905]

104.515