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: [-98.388, 210.844, 170.205, 128.375, 238.855, -71.188, -23.816]

79.27