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: [77.498, 234.955, 184.005, -48.344, 113.167]
Example Output: 112.256

Example Input: [-17.026, 165.89]
Example Output: 74.432

Example Input: [200.115, 139.316]
Example Output:
169.716