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: [-70.772, 6.883, 155.287, 91.501, -24.795, -41.265, -85.621, 14.828, 189.461]

26.167