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: [202.933, 177.244, -42.826, 213.102, 23.514, -43.793, 171.372]

100.221