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.

[-60.055, 69.92, 66.661, 67.678, 118.838, 93.501, 208.247, 24.465, 171.544]
84.533