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: [216.482, 0.935, 103.257, 204.541, 12.65, 91.719, 64.6, 70.761, 172.404]

104.15