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: [120.236, 116.311, -13.268]
Example Output: 74.426

Example Input: [23.632, 47.911, 95.884, 239.46, -68.225, 80.094, 111.959]
Example Output: 75.816

Example Input: [236.886, 169.606, 246.276, 243.852]
Example Output:
224.155