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: [-6.305, 138.079, 112.522, 52.257, -2.129]
Example Output: 58.885

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

Example Input: [164.8, 199.879, 202.853]
Example Output:
189.177