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: [134.631, 27.106]
Example Output: 80.868

Example Input: [-20.702, 4.455, 37.838, 102.751, 231.6, -23.075, 236.527, 227.109, 171.708, 46.239]
Example Output: 101.445

Example Input: [-54.916, 89.972, -47.975, -51.288, 227.81, 181.078, 244.362]
Example Output:
84.149