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: [82.439, -85.167, 100.665, -83.297]
Example Output: 3.66

Example Input: [228.031, -85.617, 36.164]
Example Output: 59.526

Example Input: [76.807, 185.792, 164.256, 34.761, 25.255, 242.503, -52.049]
Example Output:
96.761