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: [-21.562, -64.985, 42.272, 147.175, 193.278, -64.47, 8.652, 54.443, -0.039]

32.752