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: [-48.12, 192.63, 32.454, 132.703, -26.044, 140.006, -8.624, 38.438]
Example Output: 56.68

Example Input: [227.874, 175.626, 193.094, 63.963, 139.938]
Example Output: 160.099

Example Input: [-17.178, 166.895, 74.636, 58.365, 198.626, 99.851, 170.171, 144.341, 204.63, 121.716]
Example Output:
122.205