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: [-57.3, -12.788, 157.339, 116.199, 14.006, -89.286, 144.015, -37.422, 2.157, 231.79]

46.871