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: [-68.429, 130.101, 45.673]
Example Output: 35.782

Example Input: [134.631, 27.106]
Example Output: 80.868

Example Input: [96.05, -41.158, 143.014, 131.648, 173.96, -17.481, 22.924, 81.858, -2.375]
Example Output:
65.382