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: [166.542, 216.326, 98.969, -96.779, 33.532]
Example Output: 83.718

Example Input: [112.026, 20.03, 73.595, -24.957, 185.718, 36.43, 206.024]
Example Output: 86.981

Example Input: [4.951, 111.209, 212.011, 136.356, -25.242, 107.114, -87.243, 95.788, 112.183, 137.557]
Example Output:
80.468