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: [217.523, 92.701, -55.65, -89.359, 55.742, 158.634, -31.883, 206.554]
Example Output: 69.283

Example Input: [17.197, 152.985, 73.815]
Example Output: 81.332

Example Input: [114.303, 16.41, -39.174, 190.105, 242.352, -10.982, 70.776, 166.037]
Example Output:
93.728