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: [129.453, 232.284, -34.595]
Example Output: 109.047

Example Input: [233.848, -58.713, 126.623, 27.615, 62.365, 200.239, 13.38]
Example Output: 86.48

Example Input: [27.229, 18.184, 58.893, -25.078, -77.073, 235.749, 121.24, 118.874]
Example Output:
59.752