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: [227.874, 175.626, 193.094, 63.963, 139.938]
Example Output: 160.099

Example Input: [-7.057, 122.729, -78.932, 52.502, 191.819, 80.994, 29.505, -10.501]
Example Output: 47.632

Example Input: [82.95, -4.761, 0.601, 234.426, 231.683, 88.53, 126.192]
Example Output:
108.517