Definition: 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.
Input: [170.43, 73.837, 116.36, 240.099, 178.607, -22.328, 25.505, 55.959, 39.459]

97.548