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: [89.047, 195.178]
Example Output: 142.112

Example Input: [-40.246, -7.512, 174.245, -98.6]
Example Output: 6.972

Example Input: [-70.363, 139.607, 205.517, -20.302, 122.971, 169.618]
Example Output:
91.175