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: [215.561, -18.128]
Example Output: 98.716

Example Input: [50.44, 163.449, 181.067]
Example Output:
131.652

