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: [-55.198, 36.097, 190.132]
Example Output: 57.01

Example Input: [178.031, -52.967, 31.914, 174.681, 155.375, -3.831, 165.333, 10.246, -14.468]
Example Output: 71.59

Example Input: [145.468, -4.908, -83.481, -29.278, 71.597, -97.832, 129.486, 75.188, 207.193, -95.616]
Example Output:
31.782