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: [185.43, -65.359, -83.971, 30.359, -1.788, 181.168, 210.362, -90.041, -26.224, 239.651]
Example Output: 57.959

Example Input: [197.424, 44.178, 136.316, 246.48, 98.472, -31.327, 41.411]
Example Output: 104.708

Example Input: [-7.775, 55.997, 216.046]
Example Output:
88.089