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: [135.67, -94.642, 216.725, 174.675, -5.11, 0.987, 127.2, -16.118]

67.423