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: [21.65, 127.948, 174.722, -15.143, 223.442, 210.744, 222.348, 43.325]

126.13