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: [122.737, 189.477, -4.853, 150.031, 126.296, 240.809, 204.743, 29.178]
Example Output: 132.302

Example Input: [-72.554, 9.809, 27.09, 190.698]
Example Output: 38.761

Example Input: [199.389, 42.128]
Example Output:
120.758