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: [135.601, 195.027, -90.321, 4.273, 149.687, 16.342, 31.166, 120.824, -13.427, -73.626]

47.555