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: [25.889, -89.314, 75.482, -3.462, -93.25, -60.856, 16.359]

-18.45