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: [205.118, 101.679, 202.802, 144.052, -2.468, 239.04, -94.46, 214.193, 193.626]
Example Output: 133.731

Example Input: [88.77, 109.102, -86.446, 207.301, 160.91, -12.956]
Example Output: 77.78

Example Input: [174.098, 19.358, -71.29, 39.0, 202.134, 107.618, 197.578, 14.008, 211.584, -24.934]
Example Output:
86.915