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: [-59.161, -39.256, 87.516, -42.331, 126.613, 83.322, -70.322, 237.693, 86.413]

45.61