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: [-31.252, 246.934, 96.512, 19.356, -50.759, 134.528, 176.914, 17.007, 171.802]
Example Output: 86.782

Example Input: [134.631, 27.106]
Example Output: 80.868

Example Input: [192.831, 75.218, 180.682, 113.455, -84.868]
Example Output:
95.464