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: [73.603, -84.154, 222.739, 205.594, 215.842]
Example Output: 126.725

Example Input: [-6.099, 142.31]
Example Output: 68.106

Example Input: [-84.257, 150.346, 115.489, 233.173, -21.974, -78.979, 60.098, 122.944, 41.603]
Example Output:
59.827

