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: [215.854, -43.532, 51.416]
Example Output: 74.579

Example Input: [97.816, -78.424]
Example Output: 9.696

Example Input: [-32.499, 21.999, 235.435, 58.638, -57.806, 224.947, 74.782]
Example Output:
75.071