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: [137.463, -53.647, -83.336, -17.873, 135.3, 138.149, 198.283, -74.7]

47.455