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: [223.951, 2.518, 140.336, -38.799, 217.497, 212.153, 21.874]
Example Output: 111.361

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

Example Input: [-60.388, 179.882, -60.874, 161.351, -1.738, 65.73, 2.086, -71.823]
Example Output:
26.778