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: [190.227, 238.717, 36.923, -8.297, 162.975, 42.425, -39.263, 48.462, -20.609]

72.396