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: [69.573, 130.842, -69.843, -81.999, -26.657, 99.42, 158.922, 191.106, -23.293]

49.786