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: [20.574, 6.221, 203.153, -18.397, -97.477, -81.954, 173.713, 161.705, 62.545, 74.868]

50.495