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: [21.007, 48.739, -49.831, -22.699]
Example Output: -0.696

Example Input: [-95.427, -98.447]
Example Output: -96.937

Example Input: [-35.552, 8.944, 194.056, 37.354, -89.884, 126.885]
Example Output:
40.301

