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: [245.487, -82.172, -87.321, -35.714, -51.058, 29.802, -96.787]

-11.109