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: [-23.489, 230.001, -90.092, -49.689, 12.449, 187.723, 37.348, -90.419, -77.106]

15.192