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: [116.074, 213.452, 86.981]
Example Output: 138.836

Example Input: [145.697, -40.957, -46.926, -55.065, 177.211, 204.811, -94.192, -47.466]
Example Output: 30.389

Example Input: [204.239, 162.75, -27.965, 90.425, 147.912, 25.99, -22.763, 109.311]
Example Output:
86.237