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: [226.287, 114.252, -53.47, 8.606, 234.708, -31.872, 163.615]
Example Output: 94.589

Example Input: [-75.664, 192.225, 2.107, -86.22, -51.11]
Example Output: -3.732

Example Input: [-23.489, 230.001, -90.092, -49.689, 12.449, 187.723, 37.348, -90.419, -77.106]
Example Output:
15.192