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: [231.057, 71.527, 201.799, -5.17, -14.963, -35.693]
Example Output: 74.76

Example Input: [41.081, 166.314, -14.556, -84.648, -8.286]
Example Output: 19.981

Example Input: [94.777, 118.761, 0.649]
Example Output:
71.396