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: [-84.323, 103.98, 130.165, 248.69, 201.98, 160.383, 196.963, 176.567, 216.351, 18.029]

136.879