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: [198.323, 108.702, 38.704, -8.85, 57.749, 108.604, -20.56, 229.826, -85.953, 177.128]
Example Output: 80.367

Example Input: [-46.14, -0.077, 72.663, 81.035, -24.144, 66.514, 98.199]
Example Output: 35.436

Example Input: [-65.719, -51.25, 80.704, -20.724, 93.024, -58.518, 99.942, -70.64, 33.337, 149.377]
Example Output:
18.953