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: [-8.87, 232.908, 141.714, -47.559, 161.192, 203.441]
Example Output: 113.804

Example Input: [181.256, -78.191, 162.427, -90.527, 123.709, 248.073]
Example Output: 91.124

Example Input: [24.808, -2.481, 165.168, 181.391, -34.315, -68.797, 20.386, 2.081, 147.561]
Example Output:
48.422