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: [-28.982, -63.182, 22.408, 30.425, 125.743, 16.816, 96.711, 215.027, 32.552]
Example Output: 49.724

Example Input: [203.45, 193.726, 199.582, 32.046, 74.008, 170.209, 121.427, -33.882, 78.136, -8.04]
Example Output: 103.066

Example Input: [-40.261, 208.056, 139.827, 38.355, -48.351, 120.074]
Example Output:
69.617