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: [80.346, 228.37, 18.978, -42.02]
Example Output: 71.419

Example Input: [-45.826, -27.376, 126.782, -28.164, 213.819, 186.676]
Example Output: 70.985

Example Input: [160.228, -6.625, 240.76, 9.438, 173.513]
Example Output:
115.463