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: [203.45, 193.726, 199.582, 32.046, 74.008, 170.209, 121.427, -33.882, 78.136, -8.04]
Example Output: 103.066

Example Input: [248.023, 57.595, -73.013, 200.246, 142.738, -70.94, -43.129, -7.477, 200.087, 6.452]
Example Output: 66.058

Example Input: [184.146, -36.382, -26.578]
Example Output:
40.395