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: [238.315, 168.986, -67.694]
Example Output: 113.202

Example Input: [182.34, 105.105, 248.658, 104.174, -98.917, -47.707, -61.048, 241.903, -34.659, 31.89]
Example Output: 67.174

Example Input: [53.689, 92.915, 11.009, 30.726, -0.459, -32.267, 104.621]
Example Output:
37.176