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: [-97.879, 78.012, 123.477, 45.76, 180.892, 133.699, -77.9, 231.017]

77.135