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: [170.089, 199.139, 125.94, 117.265, 211.002, -87.162, 187.027, 125.863, 122.827]

130.221