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: [148.261, -51.308, -98.748, -41.832, 44.313, -41.042, -19.943]
Example Output: -8.614

Example Input: [116.074, 213.452, 86.981]
Example Output: 138.836

Example Input: [47.399, 90.972, 119.099, 171.723, 24.335]
Example Output:
90.706