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: [87.02, -25.654, -67.979, 52.368, 20.078, 160.939, 4.162, 205.092, -57.092, -68.35]
Example Output: 31.058

Example Input: [84.091, 17.564, 58.169, 6.482, 53.256, 216.444, 171.489]
Example Output: 86.785

Example Input: [-60.331, -47.903, -86.161, -52.935]
Example Output:
-61.832