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: [79.978, -44.051, 200.217, 142.486, -89.194, 55.999, 165.078, -3.615, 0.12, -44.323]
Example Output: 46.27

Example Input: [206.606, -76.103, -16.863, 44.126, 4.019, 15.088]
Example Output: 29.479

Example Input: [138.866, 176.393, 67.875]
Example Output:
127.711