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: [73.637, 249.719, 215.144, 221.034, -6.774, 15.96, -72.507, -15.652]

85.07