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: [65.486, -51.995, 170.628, -23.998, 83.128, -57.38, 130.737, 214.738]
Example Output: 66.418

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: [14.953, 7.068, 163.091, 242.816, 162.079, 133.882]
Example Output:
120.648