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: [172.252, 19.484, 201.216, -83.105, 159.707, 134.816, -11.121, -90.288, 47.703]

61.185