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: [116.94, -5.557, -52.426, -8.175, 164.035, 107.554, 42.564]

52.134