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: [45.112, 147.024, -15.583, 33.655, -60.031]
Example Output: 30.035

Example Input: [58.271, 233.766, -9.758, -40.349, 145.507, 90.294, 186.999]
Example Output: 94.961

Example Input: [88.044, 85.907, 174.993, 132.463]
Example Output:
120.352