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: [60.02, -66.628, -95.571, 114.26, 109.577, 141.08, 154.303, 228.454, 46.856, 7.365]
Example Output: 69.972

Example Input: [-17.604, 15.108, 34.328, -94.608]
Example Output: -15.694

Example Input: [125.912, 148.932, 171.771]
Example Output:
148.872