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: [-13.67, -10.677, 143.161, 202.44, 159.612, -30.358, 175.917]

89.489