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.
[43.086, 109.448, 13.846, 141.08, 228.087, 42.716, -96.96]