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: [152.683, 147.968, 62.877, -44.254, 4.344]
Example Output: 64.724

Example Input: [-79.748, 98.398, 55.667, 77.39, -20.719, 187.168, 142.334, 110.723]
Example Output: 71.402

Example Input: [88.77, 109.102, -86.446, 207.301, 160.91, -12.956]
Example Output:
77.78