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: [248.385, -40.468, -97.132]
Example Output: 36.928

Example Input: [-84.771, 60.727, 165.566, 27.782, 159.929, 167.451, -64.15]
Example Output: 61.791

Example Input: [197.324, 184.672, 79.886, -64.186]
Example Output:
99.424