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: [246.744, 206.484, 194.841]
Example Output: 216.023

Example Input: [209.13, -12.632, 247.489, 55.492, 8.967, -90.158, 193.743]
Example Output: 87.433

Example Input: [13.975, 65.09, 177.806, 134.928, -81.761, -3.372, 130.448, -6.825]
Example Output:
53.786