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: [-60.041, -56.779, 6.2, 73.114, 137.319]
Example Output: 19.963

Example Input: [-28.982, -63.182, 22.408, 30.425, 125.743, 16.816, 96.711, 215.027, 32.552]
Example Output: 49.724

Example Input: [246.965, -29.056]
Example Output:
108.954