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: [36.915, -90.664, 43.527, 134.093, -45.211, -99.342, -96.826]

-16.787