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: [-17.178, 166.895, 74.636, 58.365, 198.626, 99.851, 170.171, 144.341, 204.63, 121.716]

122.205