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: [74.381, 138.405, 189.732, 111.452, -72.375, 191.087, 73.098, 105.602, 4.542]

90.658