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.
[146.976, -87.595, 35.33, 242.36, 18.668, 237.929, -84.004]