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: [81.221, -15.412, 86.0, 60.914, 93.435, -48.008, 132.116, 132.732, 64.86]

65.318