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: [-53.388, 31.309, 19.079, -16.926, 242.421, 210.599]
Example Output: 72.182

Example Input: [231.057, 71.527, 201.799, -5.17, -14.963, -35.693]
Example Output: 74.76

Example Input: [176.95, -92.841, -33.018, 118.498, 111.391, 220.623, 48.282]
Example Output:
78.555