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: [15.748, -13.369, -79.943, -2.78, 169.174, 101.44, -84.923, 189.589, 83.541, -37.629]
Example Output: 34.085

Example Input: [-95.352, -26.358, 34.234, 162.959, 239.101, 137.014]
Example Output: 75.266

Example Input: [154.685, -24.045, 234.881, 122.942, -4.421, 45.117, 110.686, 53.464]
Example Output:
86.664