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: [74.601, 131.018, -45.91]
Example Output: 53.236

Example Input: [219.336, -29.108, -41.612, 105.709]
Example Output: 63.581

Example Input: [35.457, 222.093, 213.643, 88.716, -11.415, 190.333, 38.58, 56.243, 80.049]
Example Output:
101.522

