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: [195.575, 136.671, 133.954, 130.232, 72.902, 143.962, 228.458, 69.239, 137.6]

138.733