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.

Example Input: [187.54, -56.697, 55.301, 235.071, 176.682, 103.554, -35.29, 84.215]
Example Output: 93.797

Example Input: [-17.141, 203.132, -6.872, 155.222, -99.642]
Example Output: 46.94

Example Input: [225.907, 89.659, 168.992, -5.962, 58.185, 116.464]
Example Output:
108.874