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: [-33.746, 231.27, 122.704, -25.907, -56.96]
Example Output: 47.472

Example Input: [215.854, -43.532, 51.416]
Example Output: 74.579

Example Input: [79.82, 218.225, 156.585, 21.813, 181.413, 118.767, -40.274]
Example Output:
105.193