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.
[153.629, 221.874, -7.177, 230.895, 68.059, -58.263, 4.986, 103.63, 202.325, 122.197]