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: [203.976, 106.117, 62.128, -89.428, 180.453, 155.566, 213.868]
Example Output: 118.954

Example Input: [70.282, -54.718, 95.793, 94.043, 183.314]
Example Output: 77.743

Example Input: [246.278, 103.84, 214.867, -73.466, 230.048, -72.322, 172.891, 212.306, -78.335, 122.406]
Example Output:
107.851