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: [-17.106, 23.8, -54.195, 233.82, -99.732, -68.488, 215.616]
Example Output: 33.388

Example Input: [58.271, 233.766, -9.758, -40.349, 145.507, 90.294, 186.999]
Example Output: 94.961

Example Input: [101.494, -63.035, 144.277, 238.803]
Example Output:
105.385