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: [-2.968, 217.019, 55.0, -40.467, -2.835, -43.755, 5.173]

26.738