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: [242.148, 97.472, -15.031, 246.784, 54.233, -27.114]
Example Output: 99.749

Example Input: [117.913, 21.456, 98.401, -32.801, -20.798, 182.745, 201.277]
Example Output: 81.17

Example Input: [200.391, 96.999, 10.414]
Example Output:
102.601