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: [142.225, 243.809, -41.935, 96.795, -99.067, 222.292, 113.486, 143.726]
Example Output: 102.666

Example Input: [125.987, 140.164, 103.07, -78.923, -92.734, -96.888]
Example Output: 16.779

Example Input: [147.11, 6.136, 38.349, -12.25, 133.293, 108.999, 199.834, 66.233, -76.197, 234.451]
Example Output:
84.596