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: [117.162, 23.007, 144.696, -81.197, 55.967, -10.966, 220.074, 65.301, 199.508, -4.278]

72.927