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: [138.63, 106.759, 86.625]
Example Output: 110.671

Example Input: [248.089, 9.064, -69.315, -16.093, 95.107, -73.12, 175.054, 52.865, 95.009]
Example Output: 57.407

Example Input: [233.848, -58.713, 126.623, 27.615, 62.365, 200.239, 13.38]
Example Output:
86.48