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: [243.697, 165.796, 114.518, 207.298, 191.227]
Example Output: 184.507

Example Input: [204.235, -53.675, 201.303, 20.869]
Example Output: 93.183

Example Input: [128.328, 20.497, 96.178, 237.663, 80.568, 109.722]
Example Output:
112.159