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: [-29.727, 150.587, -28.344, 181.096, 0.275, -91.658, 169.609, -21.106, 153.48]
Example Output: 53.801

Example Input: [-41.362, 123.84, 236.661, -43.042, 53.399, 15.001, 10.159, 38.886, 74.298, 167.559]
Example Output: 63.54

Example Input: [147.664, 167.561, 244.106, -42.988, 9.425, 79.806, 239.58]
Example Output:
120.736