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: [-18.311, 190.186, -92.778, 90.838, -56.699, 126.325, 88.378, 124.585, 57.63, 166.504]

67.666