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: [-67.456, 19.727, 170.816, 47.046, -34.967, 114.317, -66.564]

26.131