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: [201.917, 240.159, 36.615]
Example Output: 159.564

Example Input: [108.26, -20.681, 127.479, -29.352]
Example Output: 46.426

Example Input: [226.355, 193.858]
Example Output:
210.106