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: [7.429, -17.94, 89.924, 22.548, 208.879, 73.573, -95.78, -82.677, 223.019]

47.664